iOS开发 大文件下载（支持断点下载）

网络连接不支持汉字，需要将 含有汉字的网址转UTF-8 编码，格式如下



NSString *pathUrl = @"http://10.0.8.8/download/iOS各种理论知识.pdf";

NSURL *url = [NSURL URLWithString:[pathUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

// 默认就是GET请求

NSURLRequest *request = [NSURLRequest requestWithURL:url];



//

// HMViewController.m

// 03-大文件下载

//

// Created by apple on 14-6-27.

// Copyright (c) 2014年 heima. All rights reserved.

//

#import "HMViewController.h"

@interface HMViewController ()

@property (weak, nonatomic) IBOutlet UIProgressView *progressView;

/**

* 写数据的文件句柄

*/

@property (nonatomic, strong) NSFileHandle *writeHandle;

/**

* 当前已下载数据的长度

*/

@property (nonatomic, assign) long long currentLength;

/**

* 完整文件的总长度

*/

@property (nonatomic, assign) long long totalLength;

/**

* 连接对象

*/

@property (nonatomic, strong) NSURLConnection *conn;

/**

* 是否在下载

*/

@property (nonatomic, assign, getter = isDownloading) BOOL downloading;

- (IBAction)start:(UIButton *)button;

@end

@implementation HMViewController

- (void)viewDidLoad

{

[super viewDidLoad];

}

// 按钮文字: "开始", "暂停"

- (IBAction)start:(UIButton *)button { // self.currentLength == 200

if (self.isDownloading) { // 暂停下载

self.downloading = NO;

[button setTitle:@"开始" forState:UIControlStateNormal];

// 取消当前的请求

[self.conn cancel];

self.conn = nil;

} else { // 开始下载

self.downloading = YES;

[button setTitle:@"暂停" forState:UIControlStateNormal];

NSURL *url = [NSURL URLWithString:@"http://192.168.1.200:8080/MJServer/resources/jre.zip"];

// 默认就是GET请求

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

// 设置请求头信息

NSString *value = [NSString stringWithFormat:@"bytes=%lld-", self.currentLength];

[request setValue:value forHTTPHeaderField:@"Range"];

self.conn = [NSURLConnection connectionWithRequest:request delegate:self];

}

}

#pragma mark - NSURLConnectionDataDelegate 代理方法

/**

* 1. 当接受到服务器的响应(连通了服务器)就会调用

*/

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{

#warning 一定要判断

if (self.totalLength) return;

// 0.文件的存储路径

NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];

NSString *filepath = [caches stringByAppendingPathComponent:@"jre.zip"];

// 1.创建一个空的文件到沙盒中

NSFileManager *mgr = [NSFileManager defaultManager];

// 刚创建完毕的大小是0字节

[mgr createFileAtPath:filepath contents:nil attributes:nil];

// 2.创建写数据的文件句柄

self.writeHandle = [NSFileHandle fileHandleForWritingAtPath:filepath];

// 3.获得完整文件的长度

self.totalLength = response.expectedContentLength;

}

/**

* 2. 当接受到服务器的数据就会调用(可能会被调用多次, 每次调用只会传递部分数据)

*/

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

// 累加长度

self.currentLength += data.length;

// 显示进度

double progress = (double)self.currentLength / self.totalLength;

self.progressView.progress = progress;

// 移动到文件的尾部

[self.writeHandle seekToEndOfFile];

// 从当前移动的位置(文件尾部)开始写入数据

[self.writeHandle writeData:data];

}

/**

* 3. 当服务器的数据接受完毕后就会调用

*/

- (void)connectionDidFinishLoading:(NSURLConnection *)connection

{

NSLog(@"connectionDidFinishLoading----");

// 清空属性值

self.currentLength = 0;

self.totalLength = 0;

// 关闭连接(不再输入数据到文件中)

[self.writeHandle closeFile];

self.writeHandle = nil;

}

/**

* 请求错误(失败)的时候调用(请求超时\断网\没有网, 一般指客户端错误)

*/

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error

{

}

@end