使用URLConnection发送GET和POST请求的简单示例

Get请求

import java.net.URLConnection;

public class HttpGet {
    public static void main(String[] args) throws Exception {
        final String spec = "http://192.168.0.115:20000/test/test.json?item=123";

        URL url = new URL(spec);
        URLConnection connection = url.openConnection();
        HttpURLConnection httpURLConnection = (HttpURLConnection) connection;

        httpURLConnection.setRequestProperty("Accept-Charset", "utf-8");
        httpURLConnection.setRequestProperty("Content-Type",
                "application/x-www-form-urlencoded");

        if (httpURLConnection.getResponseCode() == 200) {
            try (BufferedReader reader = new BufferedReader(
                    new InputStreamReader(
                            httpURLConnection.getInputStream()))) {
                String tempLine = null;
                StringBuffer resultBuffer = new StringBuffer();
                while ((tempLine = reader.readLine()) != null) {
                    resultBuffer.append(tempLine);
                }
                System.out.println(resultBuffer.toString());
            }
        }
    }
}

POST请求

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class HttpPost {
    public static void main(String[] args) throws Exception {
        final String spec = "http://192.168.0.115:20000/test/test.json";

        URL url = new URL(spec);
        URLConnection connection = url.openConnection();
        HttpURLConnection httpURLConnection = (HttpURLConnection) connection;

        httpURLConnection.setRequestProperty("Accept-Charset", "utf-8");
        httpURLConnection.setRequestProperty("Content-Type",
                "application/x-www-form-urlencoded");
        connection.setDoOutput(true);

        try (OutputStreamWriter outputStreamWriter = new OutputStreamWriter(
                httpURLConnection.getOutputStream())) {
            outputStreamWriter.write("item=123");
            outputStreamWriter.flush();
        }

        Map<String, List<String>> headerFields = httpURLConnection.getHeaderFields();
        for ( Entry<String, List<String>> entry : headerFields.entrySet()) {
            System.out.println(entry.getKey());
            for (String value : entry.getValue()) {
                System.out.println("\t" + value);
            }
        }
        
        if (httpURLConnection.getResponseCode() == 200) {
            try (BufferedReader reader = new BufferedReader(
                    new InputStreamReader(
                            httpURLConnection.getInputStream()))) {
                String tempLine = null;
                StringBuffer resultBuffer = new StringBuffer();
                while ((tempLine = reader.readLine()) != null) {
                    resultBuffer.append(tempLine);
                }
                System.out.println(resultBuffer.toString());
            }
        }
    }
}