Android通过Servlet连接阿里云服务器的mysql <一>（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
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  • 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）

  • </pre></li></ul><li><pre name="code" class="html">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";@Overrideprotected 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 blocke.printStackTrace();out.println("erro,sorry");}<span></span>//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();}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException {// TODO Auto-generated method stubif (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<String, String> 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}<span></span>//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<String , String> 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。