Flutter学习8 - 网络编程 Http

1、配置 Http 依赖

• Flutter 工具库搜索地址：https://pub.dev/

• http最新版本查看网址： https://pub.dev/packages/http

• 在 pubspec.yaml 中引入 http 插件

dependencies:
  flutter:
    sdk: flutter
  http: ^0.13.4 # 请检查并使用最新版本

• 命令行中输入 “ flutter pub get”

• 在 Dart 文件中导入

import 'package:http/http.dart' as http;

2、发送 Get 请求

import 'package:http/http.dart' as http;

void main() {
  _doGet();
}

//请求成功
_success(response) {
  var result = response.body;
  print("请求成功： $result");
}

//请求失败
_failed(response) {
  var errorCode = response.statusCode;
  var errorMessage = response.body;
  print("请求失败：errorCode: $errorCode  errorMessage: $errorMessage");
}


//请求成功码
const int SUCCESS_CODE = 200;
//请求 URL
const String GET_URL =
    'https://api.geekailab.com/uapi/test/test?requestPrams=11';

//Get 请求
_doGet() async {
  var url = Uri.parse(GET_URL);
  var response = await http.get(url);

  if (response.statusCode == SUCCESS_CODE) {
    //成功
    _success(response);
  } else {
    //失败
    _failed(response);
  }
}

3、发送 post 请求

使用 post 发送数据常用的内容类型主要有两种：

• form类型：x-www-form-urlencoded
• json类型：application/json

（1）form类型：x-www-form-urlencoded

• 请求参数必须是 Map<String, String> 类型

import 'package:http/http.dart' as http;

void main() {
  _postFormData();
}

//请求成功
_success(response) {
  var result = response.body;
  print("请求成功： $result");
}

//请求失败
_failed(response) {
  var errorCode = response.statusCode;
  var errorMessage = response.body;
  print("请求失败：errorCode: $errorCode  errorMessage: $errorMessage");
}


//请求成功码
const int SUCCESS_CODE = 200;
// post form 请求地址
const String POST_FORM_URL = 'https://api.geekailab.com/uapi/test/test';

// post 请求
_postFormData() async {
  var url = Uri.parse(POST_FORM_URL);
  //请求参数Map<String, String>
  var params = {'name': 'leon', 'age': '18'};
  var response = await http.post(url,
      body: params); //默认为x-www-form-urlencoded 格式，所以可以不用设置content-type
//  var response = await http.post(url, body: params, headers: {
//    'content-type': 'x-www-form-urlencoded'
//  }); 
  if (response.statusCode == SUCCESS_CODE) {
    //成功
    _success(response);
  } else {
    //失败
    _failed(response);
  }
}

（2）json类型：application/json

• 请求参数必须是 Map<String, String> 类型
• 可以利用 jsonEncode() 转换

import 'package:http/http.dart' as http;
import 'dart:convert';

void main() {
  _postJsonData();
}

//请求成功
_success(response) {
  var result = response.body;
  print("请求成功： $result");
}

//请求失败
_failed(response) {
  var errorCode = response.statusCode;
  var errorMessage = response.body;
  print("请求失败：errorCode: $errorCode  errorMessage: $errorMessage");
}

//请求成功码
const int SUCCESS_CODE = 200;
// post json 请求地址
const String POST_JSON_URL = 'https://api.geekailab.com/uapi/test/testJson';

// post 请求
_postJsonData() async {
  var url = Uri.parse(POST_JSON_URL);
  //请求参数 json 类型
  var params = {'name': 'leon', 'age': '18'};
  var json = jsonEncode(params);

  var response = await http.post(url, body: json, headers: {
    'content-type': 'application/json'
  }); //设置content-type为application/json

  if (response.statusCode == SUCCESS_CODE) {
    //成功
    _success(response);
  } else {
    //失败
    _failed(response);
  }
}

4、将 Response 转换成 Dart Object

• 从Response获取到的通常是json格式的string数据
• 为了使用方面我们需要将其转成Dart object，比如：转成Map或转成Model

示例：将 json string 转换成 map

var jsonString = response.body;
var map = jsonDecode(jsonString);
var result = map['message'];