java数据库操作类演示实例分享(java连接数据库)

时间:2021-05-19

复制代码 代码如下:
package org.load.demo;

import java.io.IOException;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.loadphp.simple4j.ContentValues;
import com.loadphp.simple4j.DB;
import com.loadphp.simple4j.Utils;

public class MyServlet extends HttpServlet {

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String action = req.getParameter("action");
if("show".equalsIgnoreCase(action)) {
this.findAll(req, resp);
}else if("del".equalsIgnoreCase(action)) {
this.del(req, resp);
}else if("edit".equalsIgnoreCase(action)) {
this.find(req, resp);
}else if("update".equalsIgnoreCase(action)) {
this.update(req, resp);
}else if("insert".equalsIgnoreCase(action)) {
this.insert(req, resp);
}
}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doGet(req, resp);
}

private void findAll(final HttpServletRequest req, HttpServletResponse resp) {
//DB db = this.getDB();
//List<Map<String, Object>> userList = db.findAll("*"); // 查询全部
//db.close();
//req.setAttribute("userList", userList);
//try {
//req.getRequestDispatcher("/index.jsp").forward(req, resp);
//} catch (ServletException e) {
//e.printStackTrace();
//} catch (IOException e) {
//e.printStackTrace();
//}

DB db = this.getDB();
db.findAll(new DB.QueryAllCallback() {
public void callback(List<Map<String, Object>> list) {
req.setAttribute("userList", list);
}
}, "*");

try {
req.getRequestDispatcher("/index.jsp").forward(req, resp);
} catch (ServletException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

private void del(HttpServletRequest req, HttpServletResponse resp) {
DB db = this.getDB();
db.where(new ContentValues().put("id", req.getParameter("id"))).del();
db.close();
this.findAll(req, resp);
}

private void find(final HttpServletRequest req, HttpServletResponse resp) {
DB db = this.getDB();
//Map<String, Object> map = db.where(new ContentValues().put("id", req.getParameter("id"))).find(
//"id", "name", "birthday", "pwd");

db.find(new DB.QueryCallback() {
public void callback(Map<String, Object> map) {
req.setAttribute("user", map);
}
}, "id","name","birthday");

db.close();

try {
req.getRequestDispatcher("/edit.jsp").forward(req, resp);
} catch (ServletException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

private void insert(HttpServletRequest req, HttpServletResponse resp) {
DB db = this.getDB();
db.insert(Utils.params2Array(req, 3, "null","user","birth","pwd"));
db.close();
this.findAll(req, resp);
}

private void update(HttpServletRequest req, HttpServletResponse resp) {
DB db = this.getDB();
db.where(new ContentValues().put("id", req.getParameter("id"))).update(
new ContentValues().put("name", req.getParameter("user"))
.put("pwd", Utils.md5(req.getParameter("pwd")))
.put("birthday", req.getParameter("birth")));
db.close();
this.findAll(req, resp);
}

private DB getDB() {
//DB.DRIVER = "com.mysql.jdbc.Driver"; // driver
DB.URI = "jdbc:mysql://localhost:3306/forjava"; // uri
//DB.USER = "root"; // mysql用户名
//DB.PWD = ""; // mysql密码
DB.connect("utf-8"); // 连接数据库并设置编码
return DB.init("users"); // 设置操作的表名,并返回数据库操作对象
}
}

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