Java调用Http接口(2)--HttpURLConnection调用Http接口

httpurlconnection是jdk自身提供的网络类，不需要引入额外的jar包。文中所使用到的软件版本：java 1.8.0_191。

1、get请求

public static void get() {
    httpurlconnection connection = null;
    try {
        string requestpath = "http://localhost:8080/webframe/demo/test/getuser?userid=1000&username=" + urlencoder.encode("李白", "utf-8");
        url url = new url(requestpath);
        //设置代理
        //inetsocketaddress addr = new inetsocketaddress("127.0.0.1", 8888);  
        //proxy proxy = new proxy(proxy.type.http, addr);
        //connection = (httpurlconnection)url.openconnection(proxy);
        
        connection = (httpurlconnection)url.openconnection();
        connection.setrequestmethod("get");
        connection.connect();
        
        if (connection.getresponsecode() == httpurlconnection.http_ok) {
            byte[] b = getbytesfrominputstream(connection.getinputstream());
            string back = new string(b);
            system.out.println("get返回结果：" + back);
        } else {
            system.out.println("get请求状态码：" + connection.getresponsecode());
        }
    } catch (exception e) {
        e.printstacktrace();
    } finally {
        connection.disconnect();
    }
}

2、post请求(发送键值对数据）

public static void post() {
    httpurlconnection connection = null;
    try {
        string requestpath = "http://localhost:8080/webframe/demo/test/getuser";
        url url = new url(requestpath);
        connection = (httpurlconnection)url.openconnection();
        connection.setrequestmethod("post");
        connection.setdooutput(true);
        connection.connect();
        
        string param = "userid=1000&username=李白";
        setbytestooutputstream(connection.getoutputstream(), param.getbytes());
        
        if (connection.getresponsecode() == httpurlconnection.http_ok) {
            byte[] b = getbytesfrominputstream(connection.getinputstream());
            string back = new string(b);
            system.out.println("post返回结果：" + back);
        } else {
            system.out.println("post请求状态码：" + connection.getresponsecode());
        }
    } catch (exception e) {
        e.printstacktrace();
    } finally {
        connection.disconnect();
    }
}

3、post请求(发送json数据）

public static void post2() {
    httpurlconnection connection = null;
    try {
        string requestpath = "http://localhost:8080/webframe/demo/test/adduser";
        url url = new url(requestpath);
        connection = (httpurlconnection)url.openconnection();
        connection.setrequestmethod("post");
        connection.setdooutput(true);
        connection.setrequestproperty("content-type", "application/json");
        connection.connect();
        
        string param = "{\"userid\": \"1001\",\"username\":\"杜甫\"}";
        setbytestooutputstream(connection.getoutputstream(), param.getbytes());
        
        if (connection.getresponsecode() == httpurlconnection.http_ok) {
            byte[] b = getbytesfrominputstream(connection.getinputstream());
            string back = new string(b);
            system.out.println("post2返回结果：" + back);
        } else {
            system.out.println("post2请求状态码：" + connection.getresponsecode());
        }
    } catch (exception e) {
        e.printstacktrace();
    } finally {
        connection.disconnect();
    }
}

4、上传文件及发送键值对数据

4.1、分析数据结构

通过抓包工具分析页面表单上传文件的过程，可以看出传输数据的结构：

 

4.2、根据分析出的数据结构编写代码

public static void multi() {
    string boundary = java.util.uuid.randomuuid().tostring();
    string two_hyphens = "--";
    string line_end = "\r\n";
    httpurlconnection connection = null;
    try {
        string requestpath = "http://localhost:8080/webframe/demo/test/multi";
        url url = new url(requestpath);
        connection = (httpurlconnection)url.openconnection();
        connection.setrequestmethod("post");
        connection.setdooutput(true);
        connection.setdoinput(true);
        connection.setrequestproperty("content-type", "multipart/form-data; boundary=" + boundary);
        connection.connect();
        
        stringbuffer sb = new stringbuffer();
        //封装键值对数据1
        sb.append(two_hyphens).append(boundary).append(line_end);
        sb.append("content-disposition: form-data; name=\"param1\"").append(line_end);
        sb.append(line_end);
        sb.append("参数1").append(line_end);
        
        //封装键值对数据2
        sb.append(two_hyphens).append(boundary).append(line_end);
        sb.append("content-disposition: form-data; name=\"param2\"").append(line_end);
        sb.append(line_end);
        sb.append("参数2").append(line_end);
        
        //封装文件数据
        sb.append(two_hyphens).append(boundary).append(line_end);
        sb.append("content-disposition: form-data; name=\"file\"; filename=\"a.jpg\"").append(line_end);
        sb.append("content-type: file/*").append(line_end);
        sb.append(line_end);

        setbytestooutputstream(connection.getoutputstream(), sb.tostring().getbytes());

        fileinputstream fileinputstream = new fileinputstream("d:/a.jpg");
        setbytestooutputstream(connection.getoutputstream(), fileinputstream);
        
        //写入标记结束位
        byte[] enddata = (line_end + two_hyphens + boundary + two_hyphens + line_end).getbytes();
        setbytestooutputstream(connection.getoutputstream(), enddata);
        
        if (connection.getresponsecode() == httpurlconnection.http_ok) {
            byte[] b = getbytesfrominputstream(connection.getinputstream());
            string back = new string(b);
            system.out.println("upload返回结果：" + back);
        } else {
            system.out.println("upload请求状态码：" + connection.getresponsecode());
        }
    } catch (exception e) {
        e.printstacktrace();
    } finally {
        connection.disconnect();
    }
}

4.3、上传文件方法变通

这种方式上传文件完全是模拟页面的提交行为来编码的，比较繁琐。可以把文件转成字符串，然后通过键值对传给服务端，服务端执行相反的过程来存储文件：

客户端：文件-> 字节数组->base64字符串

服务端：base64字符串-> 字节数组->文件

按照这种方式来实现应该比较容易，这里就不演示了。

5、完整例子

package com.inspur.http;

import java.io.bytearrayinputstream;
import java.io.bytearrayoutputstream;
import java.io.fileinputstream;
import java.io.ioexception;
import java.io.inputstream;
import java.io.outputstream;
import java.net.httpurlconnection;
import java.net.inetsocketaddress;
import java.net.proxy;
import java.net.url;
import java.net.urlencoder;

/**
 * 
 * 通过httpurlconnection调用http接口
 *
 */
public class httpurlconnectioncase {
    /**
     * get请求
     */
    public static void get() {
        httpurlconnection connection = null;
        try {
            string requestpath = "http://localhost:8080/webframe/demo/test/getuser?userid=1000&username=" + urlencoder.encode("李白", "utf-8");
            url url = new url(requestpath);
            //设置代理
            //inetsocketaddress addr = new inetsocketaddress("127.0.0.1", 8888);  
            //proxy proxy = new proxy(proxy.type.http, addr);
            //connection = (httpurlconnection)url.openconnection(proxy);
            
            connection = (httpurlconnection)url.openconnection();
            connection.setrequestmethod("get");
            connection.connect();
            
            if (connection.getresponsecode() == httpurlconnection.http_ok) {
                byte[] b = getbytesfrominputstream(connection.getinputstream());
                string back = new string(b);
                system.out.println("get返回结果：" + back);
            } else {
                system.out.println("get请求状态码：" + connection.getresponsecode());
            }
        } catch (exception e) {
            e.printstacktrace();
        } finally {
            connection.disconnect();
        }
    }
    
    /**
     * post请求，发送键值对数据
     */
    public static void post() {
        httpurlconnection connection = null;
        try {
            string requestpath = "http://localhost:8080/webframe/demo/test/getuser";
            url url = new url(requestpath);
            connection = (httpurlconnection)url.openconnection();
            connection.setrequestmethod("post");
            connection.setdooutput(true);
            connection.connect();
            
            string param = "userid=1000&username=李白";
            setbytestooutputstream(connection.getoutputstream(), param.getbytes());
            
            if (connection.getresponsecode() == httpurlconnection.http_ok) {
                byte[] b = getbytesfrominputstream(connection.getinputstream());
                string back = new string(b);
                system.out.println("post返回结果：" + back);
            } else {
                system.out.println("post请求状态码：" + connection.getresponsecode());
            }
        } catch (exception e) {
            e.printstacktrace();
        } finally {
            connection.disconnect();
        }
    }
    
    /**
     * post请求，发送json格式数据
     */
    public static void post2() {
        httpurlconnection connection = null;
        try {
            string requestpath = "http://localhost:8080/webframe/demo/test/adduser";
            url url = new url(requestpath);
            connection = (httpurlconnection)url.openconnection();
            connection.setrequestmethod("post");
            connection.setdooutput(true);
            connection.setrequestproperty("content-type", "application/json");
            connection.connect();
            
            string param = "{\"userid\": \"1001\",\"username\":\"杜甫\"}";
            setbytestooutputstream(connection.getoutputstream(), param.getbytes());
            
            if (connection.getresponsecode() == httpurlconnection.http_ok) {
                byte[] b = getbytesfrominputstream(connection.getinputstream());
                string back = new string(b);
                system.out.println("post2返回结果：" + back);
            } else {
                system.out.println("post2请求状态码：" + connection.getresponsecode());
            }
        } catch (exception e) {
            e.printstacktrace();
        } finally {
            connection.disconnect();
        }
    }
    
    /**
     * 上传文件及发送键值对数据
     */
    public static void multi() {
        string boundary = java.util.uuid.randomuuid().tostring();
        string two_hyphens = "--";
        string line_end = "\r\n";
        httpurlconnection connection = null;
        try {
            string requestpath = "http://localhost:8080/webframe/demo/test/multi";
            url url = new url(requestpath);
            connection = (httpurlconnection)url.openconnection();
            connection.setrequestmethod("post");
            connection.setdooutput(true);
            connection.setdoinput(true);
            connection.setrequestproperty("content-type", "multipart/form-data; boundary=" + boundary);
            connection.connect();
            
            stringbuffer sb = new stringbuffer();
            //封装键值对数据1
            sb.append(two_hyphens).append(boundary).append(line_end);
            sb.append("content-disposition: form-data; name=\"param1\"").append(line_end);
            sb.append(line_end);
            sb.append("参数1").append(line_end);
            
            //封装键值对数据2
            sb.append(two_hyphens).append(boundary).append(line_end);
            sb.append("content-disposition: form-data; name=\"param2\"").append(line_end);
            sb.append(line_end);
            sb.append("参数2").append(line_end);
            
            //封装文件数据
            sb.append(two_hyphens).append(boundary).append(line_end);
            sb.append("content-disposition: form-data; name=\"file\"; filename=\"a.jpg\"").append(line_end);
            sb.append("content-type: file/*").append(line_end);
            sb.append(line_end);

            setbytestooutputstream(connection.getoutputstream(), sb.tostring().getbytes());

            fileinputstream fileinputstream = new fileinputstream("d:/a.jpg");
            setbytestooutputstream(connection.getoutputstream(), fileinputstream);
            
            //写入标记结束位
            byte[] enddata = (line_end + two_hyphens + boundary + two_hyphens + line_end).getbytes();
            setbytestooutputstream(connection.getoutputstream(), enddata);
            
            if (connection.getresponsecode() == httpurlconnection.http_ok) {
                byte[] b = getbytesfrominputstream(connection.getinputstream());
                string back = new string(b);
                system.out.println("upload返回结果：" + back);
            } else {
                system.out.println("upload请求状态码：" + connection.getresponsecode());
            }
        } catch (exception e) {
            e.printstacktrace();
        } finally {
            connection.disconnect();
        }
    }
    
    
    /**
     * 从输入流获取数据
     * @param in
     * @return
     * @throws ioexception
     */
    private static byte[] getbytesfrominputstream(inputstream in) throws ioexception {
        bytearrayoutputstream baos = new bytearrayoutputstream();
        byte[] b = new byte[1024];
        int len;
        while ((len = in.read(b)) != -1) {
            baos.write(b, 0, len);
        }
        byte[] bytes = baos.tobytearray();
        baos.close();
        in.close();
        return bytes;
    }
    
    /**
     * 向输入流发送数据
     * @param out
     * @param bytes
     * @throws ioexception
     */
    private static void setbytestooutputstream(outputstream out, byte[] bytes) throws ioexception {
        bytearrayinputstream bais = new bytearrayinputstream(bytes);
        byte[] b = new byte[1024];
        int len;
        while ((len = bais.read(b)) != -1) {
            out.write(b, 0, len);
        }
        out.flush();
    }
    
    /**
     * 向输入流发送数据
     * @param out
     * @param bytes
     * @throws ioexception
     */
    private static void setbytestooutputstream(outputstream out, inputstream data) throws ioexception {
        byte[] b = new byte[1024];
        int len;
        while ((len = data.read(b)) != -1) {
            out.write(b, 0, len);
        }
        out.flush();
    }
    
    public static void main(string[] args) {
        get();
        post();
        post2();
        multi();
    }
}