- 秒杀接口暴露
- 执行秒杀
- 相关查询
--创建数据库脚本
CREATE DATABASE seckill;
--使用数据库
use seckill;
--创建秒杀库存表
CREATE TABLE seckill(
`seckill_id` bigint NOT NULL AUTO_INCREMENT COMMENT '商品库存id',
`name` varchar (120) NOT NULL COMMENT '商品名称',
`number` int NOT NULL COMMENT '库存数量',
`start_time` timestamp NOT NULL COMMENT '秒杀开启时间',
`end_time` timestamp NOT NULL COMMENT '秒杀结束时间',
`create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
PRIMARY KEY(seckill_id),
key idx_start_time(start_time),
key idx_end_time(end_time),
key idx_create_time(create_time)
)ENGINE=InnoDB AUTO_INCREMENT=1000 DEFAULT CHARSET=utf8 COMMENT='秒杀库存表';
--初始化数据
insert into
seckill(name,number,start_time,end_time)
values
('1元秒杀坚果tNT工作站',100,'2018-06-01 00:00:00','2018-06-02 00:00:00'),
('1元秒杀iphonex',100,'2018-06-01 00:00:00','2018-06-02 00:00:00'),
('1元秒杀坚果3',100,'2018-06-01 00:00:00','2018-06-02 00:00:00'),
('1元秒杀mac',100,'2018-06-01 00:00:00','2018-06-02 00:00:00');
--秒杀成功明细表
--用户登录认证的相关的信息
CREATE TABLE success_killed(
`seckill_id` bigint NOT NULL COMMENT '秒杀商品id',
`user_phone` bigint NOT NULL COMMENT '用户手机号',
`state` bigint NOT NULL DEFAULT -1 COMMENT '状态表示：-1：无效，0：成功，1：已付款',
`create_time` timestamp NOT NULL COMMENT '创建时间',
PRIMARY KEY (seckill_id,user_phone),
key idx_create_time(create_time)
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='秒杀成功明细表';
SeckillDao接口
public interface SeckillDao {
/**
* 减库存
* @param seckillId
* @param killTime
* @return
*/
int reduceNumber(@Param("seckillId") long seckillId, @Param("killTime") Date killTime);
/**
* 通过id查看秒杀商品
* @param seckillId
* @return
*/
Seckill queryById(long seckillId);
/**
* 根据偏移量查询秒杀商品列表
* @param offset
* @param limit
* java没有保存形参的记录，因此在运行期queryall(int offset,int limit)->queryAll(arg0,arg1)，因此加上@Param来告诉实际形参的名字
*/
List<Seckill> queryAll(@Param("offset") int offset, @Param("limit") int limit);
}
SuccessKilledDao
public interface SuccessKilledDao {
/**
* 插入购买明细，可过滤重复（联合主键）
* @param seckillId
* @param userPhone
* @return
*/
int insertSuccessKilled(@Param("seckillId") long seckillId, @Param("userPhone") long userPhone);
SuccessKilled queryByIdWithSeckill(@Param("seckillId") long seckillId,@Param("userPhone")long userPhone);
}
SeckillService接口
public interface SeckillService {
/**
* 查询所有秒杀列表
* @return
*/
List<Seckill> getSeckillList();
/**
* 查询单个秒杀记录
* @param seckillId
* @return
*/
Seckill getById(long seckillId);
/**
* 输出秒杀接口的地址
* 秒杀开启时输出接口地址
* 否则输出秒杀时间和系统时间
* @param seckillId
*/
Exposer exportSeckillUrl(long seckillId);
/**
* 执行秒杀操作
* @param seckillId
* @param userPhone
* @param md5 匹配md5是否一致，判断用户秒杀地址是否正常
*/
SeckillExecution executeSeckill(long seckillId, long userPhone, String md5) throws SeckillException,RepeatKillException,SeckillCloseException;
}
<!--spring-service.xml-->
<!--配置事务管理器-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<!--配置基于注解的声明式事务-->
<tx:annotation-driven transaction-manager="transactionManager"/>
@Override
@Transactional
public SeckillExecution executeSeckill(long seckillId, long userPhone, String md5) throws SeckillException, RepeatKillException, SeckillCloseException {
if (md5 == null || !md5.equals(getMd5(seckillId))) {
throw new SeckillException("seckill data rewrite");
}
//执行秒杀逻辑：减库存 + 记录购买行为
Date nowTime = new Date();
try {
int updateCount = seckillDao.reduceNumber(seckillId, nowTime);
if (updateCount <= 0) {
//没有更新到记录
throw new SeckillCloseException("seckill is closed");
} else {
//记录购买行为
int insertCount = successKilledDao.insertSuccessKilled(seckillId, userPhone);
if (insertCount <= 0) {
//重复秒杀
throw new RepeatKillException("seckill repeated");
} else {
SuccessKilled successKilled = successKilledDao.queryByIdWithSeckill(seckillId, userPhone);
return new SeckillExecution(seckillId, SeckillStateEnum.SUCCESS, successKilled);
}
}
} catch (SeckillCloseException e1) {
throw e1;
} catch (RepeatKillException e2) {
throw e2;
} catch (Exception e) {
LOG.error(e.getMessage(), e);
//所有编译器异常转化为运行期异常
throw new SeckillException("seckill inner error:" + e.getMessage());
}
}
-
URL设计
/模块/资源/{标示}/集合1/...
GET /seckill/list 秒杀列表
GET /seckill/{id}/detail 详情页
GET /seckill/time/now 系统时间
POST /seckill/{id}/exposer 暴露秒杀
POST /seckill/{id}/{md5}/execution 执行秒杀
- 获取秒杀列表
@RequestMapping(value = "/list", method = RequestMethod.GET)
public String getList(Long seckillId, Model model) {
List<Seckill> list = seckillService.getSeckillList();
model.addAttribute("list", list);
System.out.println("asdjk");
return "list";
}
- 商品详情页
@RequestMapping(value = "/{seckillId}/detail", method = RequestMethod.GET)
public String detail(@PathVariable("seckillId") Long seckillId, Model model) {
if (seckillId == null) {
return "redirect:/seckill/list";
}
Seckill seckill = seckillService.getById(seckillId);
if (seckill == null) {
return "forward:/seckill/list";
}
model.addAttribute("seckill", seckill);
return "detail";
}
- 暴露秒杀接口地址
@RequestMapping(value = "/{seckillId}/exposer", method = RequestMethod.POST)
@ResponseBody
public SeckillResult<Exposer> exposer(@PathVariable("seckillId") Long seckillId) {
SeckillResult<Exposer> result;
try {
Exposer exposer = seckillService.exportSeckillUrl(seckillId);
System.out.println("seckillId:" + seckillId);
result = new SeckillResult<>(true, exposer);
} catch (Exception e) {
e.printStackTrace();
result = new SeckillResult<>(false, e.getMessage());
}
System.out.println("返回结果：" + result.getData());
return result;
}
- 执行秒杀操作
@RequestMapping(value = "/{seckillId}/{md5}/execution", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
@ResponseBody
public SeckillResult<SeckillExecution> execute(@PathVariable("seckillId") Long seckillId, @PathVariable("md5") String md5, @CookieValue(value = "killPhone", required = false) Long userPhone) {
SeckillResult<SeckillExecution> result;
System.out.println("执行秒杀" + md5);
if (userPhone == null) {
return new SeckillResult<>(false, "未注册");
}
try {
SeckillExecution execution = seckillService.executeSeckill(seckillId, userPhone, md5);
return new SeckillResult<>(true, execution);
} catch (RepeatKillException e) {
SeckillExecution execution = new SeckillExecution(seckillId, SeckillStateEnum.REPEAT_KILL);
System.out.println("重复秒杀");
return new SeckillResult<>(true, execution);
} catch (SeckillCloseException e) {
SeckillExecution execution = new SeckillExecution(seckillId, SeckillStateEnum.END);
System.out.println("秒杀已结束");
return new SeckillResult<>(true, execution);
} catch (SeckillException e) {
SeckillExecution execution = new SeckillExecution(seckillId, SeckillStateEnum.INNER_ERROR);
System.out.println("内部错误");
return new SeckillResult<>(true, execution);
}
}
- 显示当前系统时间
@RequestMapping(value = "/time/now",method = RequestMethod.GET)
@ResponseBody
public SeckillResult<Long> time(){
Date now = new Date();
System.out.println(new SeckillResult(true,now.getTime()));
return new SeckillResult(true,now.getTime());
}
- 处理秒杀操作逻辑
handleSeckillkill:function(seckillId,node){
node.hide().html('<button class="btn btn-primary btn-lg" id="killBtn">开始秒杀</button>');
$.post(seckill.URL.exposer(seckillId),{},function (result) {
//在回调函数中执行交互流程
var result = eval("("+result+")")
console.log("得到结果"+result['success'] + seckillId)
if (result && result['success']){
var exposer = result['data'];
console.log(exposer)
if (exposer['exposer']) {
//开启秒杀
//获取秒杀地址
var md5 = exposer['md5'];
var killUrl = seckill.URL.execution(seckillId,md5);
console.log("killUrl : " + killUrl)
//绑定一次点击事件，降低服务器端的压力
$('#killBtn').one('click',function () {
//执行秒杀执行的操作
//1.先禁用按钮
$(this).addClass('disable');
//2.发送秒杀请求执行秒杀
$.post(killUrl,{},function (result) {
//var result = eval("("+result+")");
console.log('result:'+result);
if (result && result['success']){
var killResult = result['data'];
console.log(killResult);
var state = killResult['state'];
var stateInfo = killResult['stateInfo'];
node.html('<span class="label label-success">' + stateInfo + '</span>')
}
});
});
node.show();
}else {
//未开启秒杀
var now = exposer['now'];
var start = exposer['startTime'];
var end = exposer['endTime'];
//为防止计时结束，但未开始秒杀的情况，重新计算计时逻辑
seckill.countDown(seckillId,now,start,end);
}
}else {
console.log('result:' + result);
}
})
},
未使用redis之前，每一次暴露秒杀地址都需要从数据库进行查询再返回给java客户端，网络延迟和GC会使返回结果时间过长，使用redis之后，每次暴露秒杀地址时先从缓存查看是否存在响应数据，如果有，则直接从缓存中取数据，否则再从数据库查询，最后将查询的结果放到缓存中，方便下次使用，从而缩短查询结果时间。
- 首先需引入相应的依赖：
<!--redis客户端-->
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.9.0</version>
</dependency>
<!--redis内部没有实现序列化，因此需要添加自定义序列化依赖-->
<dependency>
<groupId>com.dyuproject.protostuff</groupId>
<artifactId>protostuff-core</artifactId>
<version>1.1.3</version>
</dependency>
<dependency>
<groupId>com.dyuproject.protostuff</groupId>
<artifactId>protostuff-runtime</artifactId>
<version>1.1.3</version>
</dependency>
- 接着设计redis缓存的逻辑
public Seckill getSeckill(long seckillId){
//redis操作逻辑
try {
Jedis jedis = jedisPool.getResource();
try {
String key = "seckill:"+seckillId;
//redis内部没有实现序列化操作，因此需要进行自定义序列化
//get->拿到字节数组bytes[]->进行反序列化—>Object
byte[] bytes = jedis.get(key.getBytes());
if (bytes != null){
//空对象
Seckill seckill = schema.newMessage();
//seckill被反序列化
ProtobufIOUtil.mergeFrom(bytes,seckill,schema);
}
} finally {
jedis.close();
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public String putSeckill(Seckill seckill){
try {
Jedis jedis = jedisPool.getResource();
//set Object->序列化->bytes[]
try {
String key = "seckill:"+seckill.getSeckillId();
byte[] bytes = ProtobufIOUtil.toByteArray(seckill,schema,
LinkedBuffer.allocate(LinkedBuffer.DEFAULT_BUFFER_SIZE));
//缓存超时
int timeout = 60*60;
String result = jedis.setex(key.getBytes(),timeout,bytes);
return result;
} finally {
jedis.close();
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
- 修改SeckillServiceImpl.java
Seckill seckill = redisDao.getSeckill(seckillId);
if (seckill == null){
seckill = seckillDao.queryById(seckillId);
if (seckill == null){
return new Exposer(false, seckillId);
}else {
redisDao.putSeckill(seckill);
}
}
**优化前：**update->insert->commit(中间需经历两次「网络延迟」和「GC」)
**优化后：**insert->update->commit(通过调整插入和更新的顺序，在进行insert操作后判断update是否需要执行（insert返回1，则插入成功，需执行update，否则插入失败，不需执行update操作），从而将延时时间缩小为原来的一半)
/* int updateCount = seckillDao.reduceNumber(seckillId, nowTime);
if (updateCount <= 0) {
//没有更新到记录
throw new SeckillCloseException("seckill is closed");
} else {
//记录购买行为
int insertCount = successKilledDao.insertSuccessKilled(seckillId, userPhone);
if (insertCount <= 0) {
//重复秒杀
throw new RepeatKillException("seckill repeated");
} else {
SuccessKilled successKilled = successKilledDao.queryByIdWithSeckill(seckillId, userPhone);
return new SeckillExecution(seckillId, SeckillStateEnum.SUCCESS, successKilled);
}
}*/
//记录购买行为
int insertCount = successKilledDao.insertSuccessKilled(seckillId, userPhone);
if (insertCount <= 0) {
//重复秒杀
throw new RepeatKillException("seckill repeated");
} else {
int updateCount = seckillDao.reduceNumber(seckillId, nowTime);
if (updateCount <= 0) {
//没有更新到记录
throw new SeckillCloseException("seckill is closed");
} else {
SuccessKilled successKilled = successKilledDao.queryByIdWithSeckill(seckillId, userPhone);
return new SeckillExecution(seckillId, SeckillStateEnum.SUCCESS, successKilled);
}
}
使用存储过程执行秒杀操作，使用存储过程使所有的数据访问都在服务器内部进行，不需传输局到其他终端，能有效缩短响应时间（之前是每进行一步都需返回到java客户端）。
- 定义存储过程
-- 秒杀执行存储过程
DELIMITER $$ -- console ; 转换为 $$
-- 定义存储过程
-- 参数: in 输入参数; out 输出参数
-- row_count():返回上一条修改类型sql(delete,insert,update)的影响行数
-- row_count: 0:未修改数据; >0:表示修改的行数; <0:sql错误/未执行修改sql
CREATE PROCEDURE `seckill`.`execute_seckill`
(in v_seckill_id bigint,in v_phone bigint,
in v_kill_time timestamp,out r_result int)
BEGIN
DECLARE insert_count int DEFAULT 0;
START TRANSACTION;
insert ignore into success_killed
(seckill_id,user_phone,create_time)
values (v_seckill_id,v_phone,v_kill_time);
select row_count() into insert_count;
IF (insert_count = 0) THEN
ROLLBACK;
set r_result = -1;
ELSEIF(insert_count < 0) THEN
ROLLBACK;
SET R_RESULT = -2;
ELSE
update seckill
set number = number-1
where seckill_id = v_seckill_id
and end_time > v_kill_time
and start_time < v_kill_time
and number > 0;
select row_count() into insert_count;
IF (insert_count = 0) THEN
ROLLBACK;
set r_result = 0;
ELSEIF (insert_count < 0) THEN
ROLLBACK;
set r_result = -2;
ELSE
COMMIT;
set r_result = 1;
END IF;
END IF;
END;
$$
-- 存储过程定义结束
- 在dao层新增
void killByProcedure(Map<String,Object> paramMap);接口，修改SeckillDao.xml
<!--mybatis调用存储过程-->
<select id="killByProcedure" statementType="CALLABLE">
call execute_seckill(
#{seckillId,jdbcType=BIGINT,mode=IN},
#{phone,jdbcType=TIMESTAMP,mode=IN},
#{killTime,jdbcType=BIGINT,mode=IN},
#{result,jdbcType=INTEGER,mode=OUT}
)
</select>
- 修改
SeckillServiceImpl.java
public SeckillExecution executeSeckillProcedure(long seckillId, long userPhone, String md5) {
if (md5 == null ||!md5.equals(getMd5(seckillId))){
return new SeckillExecution(seckillId,SeckillStateEnum.DATA_REWRITE);
}
Date killTime = new Date();
Map<String,Object> map = new HashMap<>();
map.put("seckillId",seckillId);
map.put("phone",userPhone);
map.put("killTime",killTime);
map.put("result",null);
//执行存储过程，result被赋值
try {
seckillDao.killByProcedure(map);
int result = MapUtils.getInteger(map,"result",-2);
System.out.println(result);
if (result == 1){
SuccessKilled successKilled = successKilledDao
.queryByIdWithSeckill(seckillId,userPhone);
return new SeckillExecution(seckillId,SeckillStateEnum.SUCCESS,successKilled);
}else {
return new SeckillExecution(seckillId,SeckillStateEnum.stateOf(result));
}
} catch (Exception e) {
e.printStackTrace();
return new SeckillExecution(seckillId,SeckillStateEnum.INNER_ERROR);
}
- 修改
SeckillController.java
SeckillExecution execution = seckillService.executeSeckillProcedure(seckillId,userPhone,md5);
- @Responsebody返回乱码
解决方法：
@RequestMapping(value = "/{seckillId}/{md5}/execution", method = RequestMethod.POST, produces = "application/json;charset=UTF-8")
-
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1232) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1131) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:676) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:642) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:690) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:558) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:499) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172) at javax.servlet.GenericServlet.init(GenericServlet.java:160) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1280) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1193) at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:865) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:136) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:182) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1224) ... 33 more Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException at org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter.<init>(AllEncompassingFormHttpMessageConverter.java:74) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.<init>(RequestMappingHandlerAdapter.java:189) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:170) ... 35 more Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.databind.exc.InvalidDefinitionException at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1702) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547) ... 42 more
**解决方法：**在pom.xml添加如下的依赖，我使用spring5.0.3版本，因此要添加version 2.8及以上
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.module</groupId>
<artifactId>jackson-module-jaxb-annotations</artifactId>
<version>2.9.2</version>
</dependency>
- ajax获取json数据成功，取值为undefined
解决方法：
如果jquery异步请求没做类型说明，或者以字符串方式接受，那么需要做一次对象化处理，将该字符串放于eval()中执行一次，如var result = eval("("+result+")")
原因：
eval本身的问题。 由于json是以”{}”的方式来开始以及结束的，在JS中，它会被当成一个语句块来处理，所以必须强制性的将它转换成一种表达式。