一起学Android之Intent

本文简述在android开发中intent的常见应用，仅供学习分享使用。

什么是intent?

　　intent负责对应用中一次操作的动作、动作涉及数据、附加数据进行描述，android则根据此intent的描述，负责找到对应的组件，将 intent传递给调用的组件，并完成组件的调用。因此，intent在这里起着一个媒体中介的作用，专门提供组件互相调用的相关信息，实现调用者与被调用者之间的解耦。【官方文档：an intent is an abstract description of an operation to be performed（执行某操作的抽象描述）】

intent的用途有哪些？

关联不同的组件：

1. 用来激活启动其他应用程序的组件。
2. 作为传递数据和事件的桥梁。

intent调用模式

1. 显式intent：直接指定目标组件的componentnamae，适合启动同一个应用中的其他组件，比如在某应用程序内，一个activity启动一个service。
2. 隐式intent：不直接指定目标组件的componentname class，适合启动设备中不同应用中的组件。

隐式intent常见例子

打开地图：

1  //打开地图
2     public void open_map(view v) {
3         // map point based on address
4         //uri location = uri.parse("geo:0,0?q=1600+amphitheatre+parkway,+mountain+view,+california");
5         // or map point based on latitude/longitude
6          uri location = uri.parse("geo:34.9501439901632,114.95770290767824?z=14"); // z param is zoom level
7         intent mapintent = new intent(intent.action_view, location);
8         startactivity(mapintent);
9     }

打开网页：

1  //打开指定的网页
2     public void open_url(view v){
3         uri webpage = uri.parse("http://www.baidu.com");
4         intent webintent = new intent(intent.action_view, webpage);
5         startactivity(webintent);
6     }

打电话

1 //打电话
2     public void open_tel(view v){
3         uri number = uri.parse("tel:10086");
4         intent callintent = new intent(intent.action_dial, number);
5         startactivity(callintent);
6     }

日历上设置日程

 1 //设置日历事件
 2     public void open_calendar(view v){
 3         intent calendarintent = new intent(intent.action_insert, calendarcontract.events.content_uri);
 4         calendar begintime =  calendar.getinstance();
 5         begintime.set(2012, 0, 19, 7, 30);
 6         calendar endtime = calendar.getinstance();
 7         endtime.set(2012, 0, 19, 10, 30);
 8         calendarintent.putextra(calendarcontract.extra_event_begin_time, begintime.gettimeinmillis());
 9         calendarintent.putextra(calendarcontract.extra_event_end_time, endtime.gettimeinmillis());
10         calendarintent.putextra(calendarcontract.events.title, "ninja class");
11         calendarintent.putextra(calendarcontract.events.event_location, "secret dojo");
12         startactivity(calendarintent);
13     }

 

判断intent是否有接收app

 1 public void open_chkintent(view v){
 2         intent calendarintent = new intent(intent.action_insert, calendarcontract.events.content_uri);
 3         calendar begintime =  calendar.getinstance();
 4         begintime.set(2012, 0, 19, 7, 30);
 5         calendar endtime = calendar.getinstance();
 6         endtime.set(2012, 0, 19, 10, 30);
 7         calendarintent.putextra(calendarcontract.extra_event_begin_time, begintime.gettimeinmillis());
 8         calendarintent.putextra(calendarcontract.extra_event_end_time, endtime.gettimeinmillis());
 9         calendarintent.putextra(calendarcontract.events.title, "ninja class");
10         calendarintent.putextra(calendarcontract.events.event_location, "secret dojo");
11         packagemanager packagemanager = getpackagemanager();
12         list<resolveinfo> activities = packagemanager.queryintentactivities(calendarintent, 0);
13         boolean isintentsafe = activities.size() > 0;
14         string msg=isintentsafe?"有合适的接收":"没有合适的接收";
15         toast.maketext(this,msg,toast.length_short).show();
16     }

显式调用intent

显式调用并传递参数

1 //打开一个activity
2     public void open_activity_param(view v){
3         intent intent =new intent(this,otheractivity.class);
4         intent.putextra("name","alan.hsiang");
5         intent.putextra("age",100);
6         intent.putextra("sex",true);
7         startactivity(intent);
8     }

新的activity获取参数并展示

 1 intent intent=getintent();
 2         if(intent!=null){
 3             if( intent.hasextra("name")) {
 4                 string name = intent.getstringextra("name");
 5                 integer age = intent.getintextra("age", 0);
 6                 boolean sex = intent.getbooleanextra("sex", true);
 7                 log.i("demointent", "oncreate: "+name+"--"+age+"--"+sex+" ");
 8                 edittext txtname = (edittext) this.findviewbyid(r.id.txt_name);
 9                 txtname.settext(name);
10                 log.i("demointent", "oncreate: txtname ");
11                 edittext txtage = (edittext) this.findviewbyid(r.id.txt_age);
12                 txtage.settext(age.tostring());//此处要转换成字符串，否则会被当成id，从而报错
13                 log.i("demointent", "oncreate: txtage ");
14                 radiobutton rbmale = (radiobutton) this.findviewbyid(r.id.rb_male);
15                 radiobutton rbfemale = (radiobutton) this.findviewbyid(r.id.rb_female);
16                 log.i("demointent", "oncreate: rbbutton ");
17                 rbmale.setchecked(sex);
18                 rbfemale.setchecked(!sex);
19             }
20         }

 

备注

 intent的用途还有很多，本文旨在抛砖引玉，希望大家共同学习。