Utilizing Java to implement IPFS invocation by adding files into IPFS and cat files from IPFS.
IPFS is a decentralized file system which can be used to store data in a decentralzied manner by file format.
using the instruction ipfs daemon
peer identity: 12D3KooWFS2AmXsEaLbMN3ZBjzNz95FTeSjBXiDQxU5UDy9LCw3r
IPFS：浏览器界面：localhost:5001/webui
initializing IPFS node at /Users/meng/.ipfs
小熊头像：QmeTW8KQw8X5ktoFgq44QwWBJvbcx53RnMQuDJJGvcKAha
<repositories>
<repository>
<id>jitpack.io</id>
<url>https://jitpack.io</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>com.github.ipfs</groupId>
<artifactId>java-ipfs-http-client</artifactId>
<version>v1.3.3</version>
</dependency>
</dependencies>
init IPFS
public static IPFS ipfs = new IPFS("/ip4/127.0.0.1/tcp/5001");
The data is stored in a file which is named by the data hash and stored in the directory resource/ipfsFile.
The basic operation is add and cat.
//往IPFS中添加文件
public static String add(String path) throws IOException {
NamedStreamable.FileWrapper file = new NamedStreamable.FileWrapper(new File(path));
MerkleNode addResult = ipfs.add(file).get(0);
return addResult.hash.toString();
}
//根据hash，从IPFS中拿文件
public static String cat(String ipfsHash) throws IOException {
Multihash filePointer = Multihash.fromBase58(ipfsHash);
byte[] data = ipfs.cat(filePointer);
return new String(data);
}
All the operations aiming to store data are integrated in the function IPFStorage
/*
IPFS存储流程：
1.根据内容生成哈希，作为文件名，getHash(content)，返回内容对应的哈希，在第2步中引用
2.将待存储内容作为输入，createFile(content)，返回文件路径
3.将文件路径作为输入，add(path)，存储IPFS，返回存在IPFS中的哈希
*/
public static String IPFStorage(String content) throws IOException, NoSuchAlgorithmException {
String path = createFile(content);
String ipfsHash = add(path);
System.out.println("IPFS Hash: "+ipfsHash);
return ipfsHash;
}
As is shown in IPFSDemo.Java
// store data in IPFS
String hash = IPFStorage("0617 test");
// get the data stored previously
String content = cat(hash);
System.out.println(content);