Java-Servlet开发API的例子

1、pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.sgcc</groupId>
    <artifactId>APITest</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- 添加到你的pom.xml中 -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.6</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <!-- 数据库驱动依赖，以MySQL为例 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
        </dependency>
    </dependencies>

    <packaging>war</packaging>
    <build>
        <finalName>APITest</finalName>
    </build>


</project>

 

2、代码

package com.sgcc;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.google.gson.Gson;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@WebServlet("/test")
public class DatabaseApiServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("application/json");
        String url = "jdbc:mysql://localhost:3306/test";
        String username = "root";
        String password = "Root@1234";
        List<Map<String, Object>> dataList = new ArrayList<>();

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            Connection connection = DriverManager.getConnection(url, username, password);
            String sql = "SELECT * FROM test limit 10";
            PreparedStatement statement = connection.prepareStatement(sql);
            ResultSet resultSet = statement.executeQuery();

            while (resultSet.next()) {
                Map<String, Object> data = new HashMap<>();
                data.put("id", resultSet.getString("id"));
                data.put("name", resultSet.getString("name"));
                // 添加更多列
                dataList.add(data);
            }
            resultSet.close();
            statement.close();
            connection.close();
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        Gson gson = new Gson();
        String json = gson.toJson(dataList);
        response.getWriter().write(json);
    }
}

3、打包测试

将打好的war包粘贴到tomcat的webapps文件夹中，然后在bin文件夹中启动tomcat。

在浏览器中输入地址：http://127.0.0.1:8080/APITest/test