Android 使用HTTP（get和post）方式登陆服务器

package com.wuyou.submittoserver;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;

public class MainActivity extends ActionBarActivity {

    private static final int OK = 200;
    private EditText usernameEditText;
    private EditText passwrodEditText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        usernameEditText = (EditText) findViewById(R.id.username);
        passwrodEditText = (EditText) findViewById(R.id.password);
    }

    /**
     * post方法多了三个东西：
     * ①请求的表单类型
     * ②请求的数据长度
     * ③请求的数据并且写给服务器
     */
    public void post(View view) {
        final String username = usernameEditText.getText().toString().trim();
        final String password = passwrodEditText.getText().toString().trim();
        //Android默认模拟器外部的地址为10.0.2.2，而不是localhost和127.0.0.1
        final String serverPath = "http://10.0.2.2:8080/LoginServlet";
        if (TextUtils.isEmpty(username) || TextUtils.isEmpty(password)) {
            //给出提示：账号密码不许为空
        } else {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        //向服务器请求的数据
                        String data = "username=" + URLEncoder.encode(username,"UTF-8") + "&password=" + URLEncoder.encode(password,"UTF-8");
                        URL url = new URL(serverPath);
                        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                        httpURLConnection.setRequestMethod("POST");
                        httpURLConnection.setConnectTimeout(3000);
                        httpURLConnection.setDoOutput(true);//打开输出流，以便向服务器提交数据
                        //设置请求体的类型是文本类型
                        httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
                        //设置请求体的长度
                        httpURLConnection.setRequestProperty("Content-Length", String.valueOf(data.length()));
                        //获得输出流，向服务器写入数据
                        OutputStream outputStream = httpURLConnection.getOutputStream();
                        outputStream.write(data.getBytes());

                        int responseCode = httpURLConnection.getResponseCode();
                        if (200 == responseCode) {
                            InputStream inputStream = httpURLConnection.getInputStream();
                            final String responseMsg = StreamTool.getString(inputStream);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(MainActivity.this, responseMsg, Toast.LENGTH_LONG).show();
                                }
                            });
                        } else {
                            System.out.println("responseCode = " + responseCode);
                            //连接服务器出错，错误代码为：responseCode 根据代码值告诉用户出错的原因
                            //....
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
    }

    public void get(View view) {
        final String username = usernameEditText.getText().toString().trim();
        final String password = passwrodEditText.getText().toString().trim();
        //Android默认模拟器外部的地址为10.0.2.2，而不是localhost和127.0.0.1
        final String serverPath = "http://10.0.2.2:8080/LoginServlet";
        if (TextUtils.isEmpty(username) || TextUtils.isEmpty(password)) {
            //给出提示：账号密码不许为空
        } else {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        //使用GET方式请求服务器只能这样
                        URL url = new URL(serverPath + "?username=" + URLEncoder.encode(username,"UTF-8") + "&password=" + URLEncoder.encode(password,"UTF-8"));
                        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                        httpURLConnection.setRequestMethod("GET");
                        httpURLConnection.setConnectTimeout(5000);
                        httpURLConnection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20100101 Firefox/22.0");
                        int responseCode = httpURLConnection.getResponseCode();
                        if (200 == responseCode) {
                            InputStream inputStream = httpURLConnection.getInputStream();
                            final String responseMsg = StreamTool.getString(inputStream);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(MainActivity.this, responseMsg, Toast.LENGTH_LONG).show();
                                }
                            });
                        } else {
                            System.out.println("responseCode = " + responseCode);
                            //连接服务器出错，错误代码为：responseCode 根据代码值告诉用户出错的原因
                            //....
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
    }
}

class StreamTool {
    public static String getString(InputStream inputStream) throws IOException {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byte[] buf = new byte[1024];
        int length;
        while((length = inputStream.read(buf)) >0) {
            byteArrayOutputStream.write(buf, 0 ,length);
        }
        byte[] stringBytes = byteArrayOutputStream.toByteArray();
        String str = new String(stringBytes);
        return str;
    }
}

界面就不写了。

要注意几个地方：

①模拟器访问本机服务器127.0.01（locahost）的话，使用的地址是：10.0.2.2

②post比get方法多了三个要发送的数据头(header)