Android中使用retrofit2进行网络get请求查询数据和post请求上传文件

心已赠人 2023-10-05 16:02 24阅读 0赞

## 场景 ##

### Retrofit2 ###

Retrofit 是对 OkHttp 的封装，是主流的网络框架。

适用于Android 和 Java 的类型安全的HTTP客户端，由Square提供的。

Retrofit是一种HTTP客户端框架，使用它，我们可以完成有关HTTP的工作。

Retrofit Github 主页：

[https://github.com/square/Retrofit][https_github.com_square_Retrofit]

注：

博客：  
[https://blog.csdn.net/badao\_liumang\_qizhi ][https_blog.csdn.net_badao_liumang_qizhi]  
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## 实现 ##

### 导入依赖 ###

在build.gradle中添加依赖

//Retrofit（网络请求框架）
        implementation 'com.squareup.retrofit2:retrofit:2.5.0'
        implementation 'com.squareup.retrofit2:converter-gson:2.5.0'

添加位置

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

然后点击右上角的Sync now

注意：这里不能导入OkHttp与Gson，Retrofit内部已经包含这两个框架，否则会导致版本冲突。

### 打卡网络权限 ###

在AndroidManifest中添加网络权限。

<uses-permission android:name="android.permission.INTERNET" />

### 搭建Http客户端 ###

为了在调用接口时方便我们新建一个单例模式的类WebClient去构造Retrofit的实例

在src下包路径下新建web包，包下新建webclient类

package com.badao.badaoimclient.web;
    
    import android.util.Log;
    
    import retrofit2.Retrofit;
    import retrofit2.converter.gson.GsonConverterFactory;
    
    public class WebClient {
    
        private static ApiService INSTANCE;
    
        private static final String BASE_URL = "http://你的后台服务的ip:8000/";
    
        public static ApiService getInstance() {
            if (INSTANCE == null) {
                synchronized (ApiService.class) {
                    if (INSTANCE == null) {
                        INSTANCE = new Retrofit.Builder().baseUrl(BASE_URL).addConverterFactory(GsonConverterFactory.create()).build().create(ApiService.class);
                        Log.i("INSTANCE",BASE_URL);
                    }
                }
            }
            return INSTANCE;
        }
    
    }

这里指定的BASE\_RUL就是你后台服务地址的ip+端口号，最后要带一个斜杠。

然后客户端需要返回一个接口类ApiService，这个接口类是自定义的。

新建接口类ApiService

package com.badao.badaoimclient.web;
    
    import com.badao.badaoimclient.bean.ImUserBean;
    import com.badao.badaoimclient.bean.UploadBean;
    import okhttp3.MultipartBody;
    import retrofit2.Call;
    import retrofit2.http.GET;
    import retrofit2.http.Multipart;
    import retrofit2.http.POST;
    import retrofit2.http.Part;
    
    public interface ApiService {
    
        /*无参GET请求 */
        //没有数据就填 '.' 或者 '/'
        //获取通讯录接口
        @GET("system/imuser/listForApp")
        Call<ImUserBean> getImUserList();
    
        //文件上传接口
        @Multipart
        @POST("/common/upload")
        Call<UploadBean> upload(@Part MultipartBody.Part file);
    
    }

这里接口类中有两个方法，一个是get方法请求数据，一个是post方法上传文件。

先看这里的get请求的接口，接口的返回值ImUserBean是根据服务接口返回的Json数据生成的bean。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

怎样根据Json数据生成实体Bean参考如下：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/110426851][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_110426851]

生成的实体ImUserBean如下

package com.badao.badaoimclient.bean;
    
    import com.google.gson.annotations.SerializedName;
    
    import java.util.List;
    
    public class ImUserBean {
    
        private int total;
        private int code;
        private Object msg;
        private List<RowsBean> rows;
    
        public int getTotal() {
            return total;
        }
    
        public void setTotal(int total) {
            this.total = total;
        }
    
        public int getCode() {
            return code;
        }
    
        public void setCode(int code) {
            this.code = code;
        }
    
        public Object getMsg() {
            return msg;
        }
    
        public void setMsg(Object msg) {
            this.msg = msg;
        }
    
        public List<RowsBean> getRows() {
            return rows;
        }
    
        public void setRows(List<RowsBean> rows) {
            this.rows = rows;
        }
    
        public static class RowsBean {
    
            @SerializedName("id")
            private int idX;
            @SerializedName("imNum")
            private String imNumX;
            @SerializedName("canOnline")
            private int canOnlineX;
    
            public int getIdX() {
                return idX;
            }
    
            public void setIdX(int idX) {
                this.idX = idX;
            }
    
            public String getImNumX() {
                return imNumX;
            }
    
            public void setImNumX(String imNumX) {
                this.imNumX = imNumX;
            }
    
            public int getCanOnlineX() {
                return canOnlineX;
            }
    
            public void setCanOnlineX(int canOnlineX) {
                this.canOnlineX = canOnlineX;
            }
        }
    }

然后真正调用的接口的url就是

上面配置的BASE\_URL加上你的接口方法中配置的url

### Get接口调用 ###

在需要调用get接口请求数据的地方

//异步请求通讯录
            WebClient.getInstance().getImUserList().enqueue(new Callback<ImUserBean>() {
                @Override
                public void onResponse(Call<ImUserBean> call, Response<ImUserBean> response) {
                    Log.i("response",response.toString());
                    if(response.code()==200) {
                        //获取请求的数据并进行后续操作
                        ImUserBean userBean = response.body();
                        rowsBeanList = userBean.getRows();
                        myAdapter = new MyAdapter(rowsBeanList);
                        listView.setAdapter(myAdapter);
                    }
                }
                @Override
                public void onFailure(Call<ImUserBean> call, Throwable t) {
                    Log.i("onFailure",t.toString());
                }
            });
        }

通过它的回调方法来获取响应码和响应体。

此后台接口是用SpringBoot写成，后台get接口部分实现

@GetMapping("/listForApp")
        @ResponseBody
        public TableDataInfo listGet(ImUser imUser)
        {
            startPage();
            List<ImUser> list = imUserService.selectImUserList(imUser);
            return getDataTable(list);
        }

其中在getDataTable中最终返回

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

调用一下此接口可以看到其响应码为200

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3][]

响应体就是上面的json数据

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 4][]

然后可以将get请求的数据通过适配器显示在ListView上

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 5][]

关于适配器的使用参照如下：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/111240545][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_111240545]

### POST请求上传文件 ###

首先在ApiService中添加接口声明

//文件上传接口
        @Multipart
        @POST("/common/upload")
        Call<UploadBean> upload(@Part MultipartBody.Part file);

然后在需要用到进行文件上传的地方

//上传语音文件到服务器
                    RequestBody requestBody = RequestBody.create(MediaType.parse("multipart/form-data"), file);
                    MultipartBody.Part part = MultipartBody.Part.createFormData("file", file.getName(), requestBody);
                    WebClient.getInstance().upload(part).enqueue(new Callback<UploadBean>() {
                        @Override
                        public void onResponse(Call<UploadBean> call, Response<UploadBean> response) {
                            if(response.code()==200)
                            {
                                //对服务器地址进行赋值
                                chatItem.setRemoteContent(response.body().getFileName());
    
                            }
                            else {
                                Toast.makeText(App.context,"服务器返回"+response.code(),Toast.LENGTH_SHORT).show();
                                return;
                            }
                        }
    
                        @Override
                        public void onFailure(Call<UploadBean> call, Throwable t) {
                            Toast.makeText(App.context,t.toString(),Toast.LENGTH_SHORT).show();
                        }
                    });

其中file就是需要进行上传的文件，需要构造出一个part对象，然后下面是两个回调方法

触发post方法后，构造part对象成功

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 6][]

后台使用sprinboot写的post接口

/**
         * 通用上传请求
         */
        @PostMapping("/common/upload")
        @ResponseBody
        public AjaxResult uploadFile(MultipartFile file) throws Exception
        {
            try
            {
                // 上传文件路径
                String filePath = RuoYiConfig.getUploadPath();
                // 上传并返回新文件名称
                String fileName = FileUploadUtils.upload(filePath, file);
                String url = serverConfig.getUrl() + fileName;
                AjaxResult ajax = AjaxResult.success();
                ajax.put("fileName", fileName);
                ajax.put("url", url);
                return ajax;
            }
            catch (Exception e)
            {
                return AjaxResult.error(e.getMessage());
            }
        }

后台接收到请求后

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 7][]

后台返回给Android后

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 8][]

###     ###

[https_github.com_square_Retrofit]: https://github.com/square/Retrofit
[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi
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[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_110426851]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/110426851
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20201217113157493.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
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[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_111240545]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/111240545
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