1.概述

使用spring boot作为后端框架与Android端配合mysql进行基本的交互,包含了最基本的增删查改功能.

2.开发环境

win10
IDEA
tomcat9.0.27
mysql8.0.17
spring boot

3.后端

(1)新建一个spring boot项目

可以看这里

(2)Entity

新建User类作为实体类:

package com.test;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;@Entitypublic class User {    @Id    @GeneratedValue(strategy = GenerationType.AUTO)    private Integer id;    private String name;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

这里其实使用的是(1)中的代码,里面有详细的解释.

(3)Repository

新建UserRepository去实现增删查改:

package com.test;import org.springframework.data.jpa.repository.Modifying;import org.springframework.data.jpa.repository.Query;import org.springframework.data.repository.CrudRepository;import org.springframework.data.repository.query.Param;import org.springframework.stereotype.Repository;import org.springframework.web.bind.annotation.RequestParam;import java.util.List;@Repositorypublic interface UserRepository extends CrudRepository{    @Query(value = "select * from user where name = ?1",nativeQuery = true)    public List findByName(String name);    @Modifying    @Query(value = "delete from user where name = ?1",nativeQuery = true)    public int deleteByName(String name);}

由于CrudRepository中已经包含了"增"与"改",所以按需要实现自己的"查"与"删"即可.
CrudRepository的api很简单,官方文档在这里.

"增"使用save即可,参数为实体类
"删"使用deleteById,通过主键删除,若不想通过主键删除可以自己编写sql,像上面一样
"查"使用findAll或findById,自定义查找的话需要自己编写sql.
"改"也可使用save,注意需要设置主键.

@Query用于设置sql,nativeQuery表示使用原生sql.

(4)Service

新建一个MainService.java

package com.test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import javax.transaction.Transactional;import java.util.List;@Transactional@Servicepublic class MainService {    @Autowired    private UserRepository userRepository;    public Iterable getAllUsers()    {        return userRepository.findAll();    }    public List findByName(String name)    {        return userRepository.findByName(name);    }    public boolean add(String name)    {        User user = new User();        user.setName(name);        userRepository.save(user);        return true;    }    public boolean modify(Integer id,String name)    {        User user = new User();        user.setName(name);        user.setId(id);        userRepository.save(user);        return true;    }    public boolean deleteByName(String name)    {        return userRepository.deleteByName(name) != 0;    }}

getAllUsers()返回所有行,Iterable类型
findByName()根据name返回所有name相同的行.
add直接使用了save,由于save返回的是实体类,原本的代码是这样写的:
```
return userRepository.save(user) != null;
```
但是文档说了不会为null,所以只能强制返回true了.
modify使用了id与name作为参数,新建一个user,将其作为setter的参数,然后交给save.
deleteByName使用了自定义的删除函数,返回的是int,在UserRepository中这个int代表sql影响的行数,删除成功则行数不为0,删除失败,或者没有这行数据则行数为0.因此将返回值与0进行比较.

(5)Controller

package com.test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.*;import java.util.List;@Controller@RequestMapping(path = "/demo")public class MainController {    @Autowired    private MainService mainService;    @GetMapping(path = "/getAll")    public @ResponseBody Iterable getAllUsers()    {        return mainService.getAllUsers();    }    @PostMapping(path = "/get")    public @ResponseBody List findByName(String name)    {        return mainService.findByName(name);    }    @PostMapping(path = "/add")    public @ResponseBody boolean add(@RequestParam String name)    {        return mainService.add(name);    }    @PostMapping(path = "/modify")    public @ResponseBody boolean modify(@RequestParam Integer id,@RequestParam String name)    {        return mainService.modify(id,name);    }    @PostMapping(path = "/delete")    public @ResponseBody boolean deleteByName(@RequestParam String name)    {        return mainService.deleteByName(name);    }}

Controller主要就是几个注解,除了getAllUsers使用Get外,其他的都是用Post.另外就是路径设置,直接在path中设置即可.
后端的话到这里就基本完成了,剩下的打包部署操作就.....

4.前端

什么新建工程之类的就不说了.
直接上MainActivity:

package com.example.myapplication;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;import android.os.Looper;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;import com.alibaba.fastjson.JSONArray;import com.example.myapplication.model.dao.*;import com.example.myapplication.model.entity.*;import java.io.IOException;import java.util.List;import okhttp3.FormBody;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button register = findViewById(R.id.register);        register.setOnClickListener(                v ->                {                    new Thread(()-> {                        OkHttpClient okHttpClient = new OkHttpClient();                        String name = ((EditText) findViewById(R.id.name)).getText().toString();                        FormBody formBody = new FormBody.Builder().add("name", name).build();                        Request request = new Request.Builder()                                .url(Constant.ADD)                                .post(formBody)                                .build();                        try (Response response = okHttpClient.newCall(request).execute()) {                            Looper.prepare();                            if (Boolean.parseBoolean(response.body().string()))                            {                                Toast.makeText(this, "注册成功", Toast.LENGTH_SHORT).show();                            }                            else                            {                                Toast.makeText(this, "注册失败", Toast.LENGTH_SHORT).show();                            }                            Looper.loop();                        } catch (IOException e) {                            e.printStackTrace();                        }                    }).start();                }        );        Button login = findViewById(R.id.login);        login.setOnClickListener(                v ->                {                    new Thread(()-> {                        OkHttpClient okHttpClient = new OkHttpClient();                        String name = ((EditText) findViewById(R.id.name)).getText().toString();                        FormBody formBody = new FormBody.Builder().add("name", name).build();                        Request request = new Request.Builder()                                .url(Constant.GET)                                .post(formBody)                                .build();                        try (Response response = okHttpClient.newCall(request).execute()) {                            List users = JSONArray.parseArray(response.body().string(),User.class);                            Looper.prepare();                            if(users.size() == 0)                            {                                Toast.makeText(this,"登录失败",Toast.LENGTH_SHORT).show();                            }                            else                            {                                Toast.makeText(this,"登录成功",Toast.LENGTH_SHORT).show();                            }                            Looper.loop();                        } catch (IOException e) {                            e.printStackTrace();                        }                    }).start();                }        );        Button delete = findViewById(R.id.delete);        delete.setOnClickListener(                v ->                {                    new Thread(()-> {                        OkHttpClient okHttpClient = new OkHttpClient();                        String name = ((EditText) findViewById(R.id.name)).getText().toString();                        FormBody formBody = new FormBody.Builder().add("name", name).build();                        Request request = new Request.Builder()                                .url(Constant.DELETE)                                .post(formBody)                                .build();                        try (Response response = okHttpClient.newCall(request).execute()) {                            Looper.prepare();                            if (Boolean.parseBoolean(response.body().string()))                            {                                Toast.makeText(this, "删除成功", Toast.LENGTH_SHORT).show();                            }                            else                            {                                Toast.makeText(this, "删除失败", Toast.LENGTH_SHORT).show();                            }                            Looper.loop();                        } catch (IOException e) {                            e.printStackTrace();                        }                    }).start();                }        );        Button modify = findViewById(R.id.modify);        modify.setOnClickListener(                v ->                {                    new Thread(()-> {                        OkHttpClient okHttpClient = new OkHttpClient();                        String name = ((EditText) findViewById(R.id.name)).getText().toString();                        String id = ((EditText)findViewById(R.id.id)).getText().toString();                        FormBody formBody = new FormBody.Builder()                                .add("name", name)                                .add("id",id)                                .build();                        Request request = new Request.Builder()                                .url(Constant.MODIFY)                                .post(formBody)                                .build();                        try (Response response = okHttpClient.newCall(request).execute()) {                            Looper.prepare();                            if (Boolean.parseBoolean(response.body().string()))                            {                                Toast.makeText(this, "修改成功", Toast.LENGTH_SHORT).show();                            }                            else                            {                                Toast.makeText(this, "修改失败", Toast.LENGTH_SHORT).show();                            }                            Looper.loop();                        } catch (IOException e) {                            e.printStackTrace();                        }                    }).start();                }        );    }}

(1)增

OkHttpClient okHttpClient = new OkHttpClient();String name = ((EditText) findViewById(R.id.name)).getText().toString();FormBody formBody = new FormBody.Builder().add("name", name).build();Request request = new Request.Builder()        .url(Constant.ADD)        .post(formBody)        .build();try (Response response = okHttpClient.newCall(request).execute()) {    Looper.prepare();    if (Boolean.parseBoolean(response.body().string()))    {        Toast.makeText(this, "注册成功", Toast.LENGTH_SHORT).show();    }    else    {        Toast.makeText(this, "注册失败", Toast.LENGTH_SHORT).show();    }    Looper.loop();} catch (IOException e) {    e.printStackTrace();}

使用okhttp,通过FormBody设置参数,然后创建Request通过OkHttpClient发送.
由于后端"增"的方法返回的是一个true,因此这里将response.body().string()转换成boolean判断是否操作成功.
稍微提一下,

Looper.prepare();Looper.loop();

这两行可以在非UI线程中使用Toast.

(2)删

OkHttpClient okHttpClient = new OkHttpClient();String name = ((EditText) findViewById(R.id.name)).getText().toString();FormBody formBody = new FormBody.Builder().add("name", name).build();Request request = new Request.Builder()        .url(Constant.DELETE)        .post(formBody)        .build();try (Response response = okHttpClient.newCall(request).execute()) {    Looper.prepare();    if (Boolean.parseBoolean(response.body().string()))    {        Toast.makeText(this, "删除成功", Toast.LENGTH_SHORT).show();    }    else    {        Toast.makeText(this, "删除失败", Toast.LENGTH_SHORT).show();    }    Looper.loop();} catch (IOException e) {    e.printStackTrace();}

删这部分也是差不多的,就是改一下url,然后....然后没有了....~~好像很简单的样子?~~

(3)查

OkHttpClient okHttpClient = new OkHttpClient();String name = ((EditText) findViewById(R.id.name)).getText().toString();FormBody formBody = new FormBody.Builder().add("name", name).build();Request request = new Request.Builder()        .url(Constant.GET)        .post(formBody)        .build();try (Response response = okHttpClient.newCall(request).execute()) {    List users = JSONArray.parseArray(response.body().string(),User.class);    Looper.prepare();    if(users.size() == 0)    {        Toast.makeText(this,"登录失败",Toast.LENGTH_SHORT).show();    }    else    {        Toast.makeText(this,"登录成功",Toast.LENGTH_SHORT).show();    }    Looper.loop();} catch (IOException e) {    e.printStackTrace();}

查这里注意一下后端返回的是List,这里借助阿里的fastjson转换成List.

List users = JSONArray.parseArray(response.body().string(),User.class);

然后判断有没有的话就判断长度是否为0即可.

(4)改

OkHttpClient okHttpClient = new OkHttpClient();String name = ((EditText) findViewById(R.id.name)).getText().toString();String id = ((EditText)findViewById(R.id.id)).getText().toString();FormBody formBody = new FormBody.Builder()        .add("name", name)        .add("id",id)        .build();Request request = new Request.Builder()        .url(Constant.MODIFY)        .post(formBody)        .build();try (Response response = okHttpClient.newCall(request).execute()) {    Looper.prepare();    if (Boolean.parseBoolean(response.body().string()))    {        Toast.makeText(this, "修改成功", Toast.LENGTH_SHORT).show();    }    else    {        Toast.makeText(this, "修改失败", Toast.LENGTH_SHORT).show();    }    Looper.loop();} catch (IOException e) {    e.printStackTrace();}

改的话只需一个额外的ID参数,在FormBody中add一个即可,不难.

(5)界面

<?xml version="1.0" encoding="utf-8"?>

界面不详细说了,不难.

(6)依赖与其他

注意一下依赖,还有设置java8.

(7)网络权限

这个作者之前的文章有说.
请看这里.

5.测试

这是"原本的"数据库.
~~没办法为了测试.~~

注册一个.

看看数据库:

试试登录一个不存在的.

修改:

最后是删除:

删除一个不存在的会删除失败.

6.源码

github
码云

后端spring boot+前端Android交互+mysql增删查改