Android通过Servlet连接阿里云服务器的mysql （servlet编程）

• 最近想做一些跟服务器相关的Android手机端开发，所以入手了半年的阿里云服务器，给服务器选择Linux的系统刚好也学习下Linux的相关的知识。
• 废话不多说，通过Eclipse的IDE进行服务器端的开发。实现代码是根据LFF_Coder改写的。
  • 新建Dynamic Web Project
  • 
    
  • 由于要连接Mysql，所以创建Libs文件夹， 添加mysql-connector-java-5.1.29-bin.jar，然后Add to build path。
  • 在Java Resources文件夹下新建class（例子：hello.class）

• import java.io.IOException;
  import java.io.PrintWriter;
  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import com.google.gson.Gson;
  
  public class hello extends javax.servlet.http.HttpServlet {
  
  	private static final long serialVersionUID = 1L;
  
  	static String driver = "com.mysql.jdbc.Driver";
  	static String url = "jdbc:mysql://云服务器ip:3306/mydb";
  	static String user = "用户";
  	static String password = "密码";
  
  	@Override
  	protected void doGet(HttpServletRequest req, HttpServletResponse res)
  			throws ServletException, IOException {
  		// TODO Auto-generated method stub
  		// resp.getWriter().write("hello，tomcat");
  
  		res.setContentType("application/json;charset=utf-8");
  		req.setCharacterEncoding("utf-8");
  
  		PrintWriter out = res.getWriter();
  		 		
  		HashMap resultList = new HashMap<>();
  		try {
  			resultList = getData();
  		} catch (Exception e) {
  			// TODO Auto-generated catch block
  			e.printStackTrace();
  			out.println("erro,sorry");
  			
  		}
  		//将返回的数据（HashMap通过Gson以Json的方式返回客户端）
  		  Gson gson = new Gson();
  		  String result = gson.toJson(resultList);
  		  out.write(result);
  		  out.close();
  
  	}
  
  	@Override
  	protected void doPost(HttpServletRequest req, HttpServletResponse res)
  			throws ServletException, IOException {
  		// TODO Auto-generated method stub
  		if (null == req) {
  			return;
  		}
  		res.setContentType("application/json;charset=utf-8");
  		req.setCharacterEncoding("utf-8");
  		res.setCharacterEncoding("utf-8");
  
  		PrintWriter out = res.getWriter();
  		String username = req.getParameter("user_name");
  		String password = req.getParameter("password");
  		if (username.equals("admin")) {
  			if (password.equals("123")) {
  				out.println("0"); // /< 正确
  			} else {
  				out.println("2"); // /< 密码错误
  			}
  		} else {
  			out.println("1"); // /< 用户名错误
  		}
  		out.flush();
  		out.close();
  	}
  
  	// 到Mysql获得数据
  	private HashMap getData() throws Exception {
  
  		try {
  			Class.forName(driver);
  			System.out.println("成功链接");
  		} catch (Exception e) {
  			// TODO: handle exception
  		}
  
  		Connection conn = null;
  		try {
  			conn = (Connection) DriverManager
  					.getConnection(url, user, password);
  			System.out.println("成功connection");
  		} catch (Exception e) {
  			// TODO: handle exception
  		}
  		//从userinfo 表中遍历出所有记录，然后将username 与 passwd字段保存在Hashmap中
  		Statement statement = (Statement) conn.createStatement();
  		String sql = null;
  		sql = "select * from userinfo";
  		ResultSet rs = statement.executeQuery(sql);
  		List resultList = new ArrayList();
  		HashMap hash = new HashMap<>();
  		
  		while (rs.next()) {
  			resultList.add(rs.getString("username"));
  			hash.put(rs.getString("username"), rs.getString("passwd"));
  		}
  
  		
  		return hash;
  	}
  
  }
  

  
  
• 将servlet程序导出，右键-->export-->War file。
• 将War包上传至云服务的Tomcat的Webapps文件夹下，记住，工程所依赖的包都得上传到Tomcat的Lib文件夹下（因为这个问题折腾了半天！）
• 重启Tomcat服务即可。