android学习笔记（1）

09：布局
LineaerLayout(线性布局)、RelativeLayout(相对布局)：android:layout_toRightOf,android:layout_alignTop
TableLayout(表格布局)、FrameLayout(帧布局)
常用RelativeLayout(相对布局)、TableLayout(表格布局)
10：测试
在应用配置文件导测试依赖包
<uses-library android:name="android.test.runner" />
<instrumentation android:name="android.test.InstrumentationTestRunner"
  android:targetPackage="cn.itcast.test" android:label="Tests for My App" />
12：文件读写
应用内文件的保存读取
context.openFileOutput(filename, Context.MODE_PRIVATE);//保存
context.openFileInput(filename);//读取
13：文件模式
4种模式
Context.MODE_PRIVATE 覆盖写，私有
Context.MODE_APPEND  追加写，私有
Context.MODE_WORLD_WRITEABLE 可写
Context.MODE_WORLD_READABLE 可读 
Context.MODE_WORLD_READABLE+Context.MODE_WORLD_WRITEABLE 可读写


14：SD卡文件读写
//获取SDCard路径
Environment.getExternalStorageDirectory();
//判断SDCard是否存在，并且可以读写
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){}


15：pull解析器解析XML
//读取XML
XmlPullParser pullParser=Xml.newPullParser();
pullParser.setInput(inputStream,"UTF-8");
int event = pullParser.getEventType();
while(event != XmlPullParser.END_DOCUMENT){
switch (event) {
case XmlPullParser.START_DOCUMENT:
persons = new ArrayList<Person>();
break;

case XmlPullParser.START_TAG:
if("person".equals(pullParser.getName())){
int id = new Integer(pullParser.getAttributeValue(0));
person = new Person();
person.setId(id);
}
if("name".equals(pullParser.getName())){
String name = pullParser.nextText();
person.setName(name);
}
if("age".equals(pullParser.getName())){
int age = new Integer(pullParser.nextText());
person.setAge(age);
}
break;

case XmlPullParser.END_TAG:
if("person".equals(pullParser.getName())){
persons.add(person);
person = null;
}
break;
}
event = pullParser.next();
}
//写XML
XmlSerializer serializer = Xml.newSerializer();
serializer.setOutput(out, "UTF-8");
serializer.startDocument("UTF-8", true);
serializer.startTag(null, "persons");
for(Person person : persons){
serializer.startTag(null, "person");
serializer.attribute(null, "id", person.getId().toString());

serializer.startTag(null, "name");
serializer.text(person.getName());
serializer.endTag(null, "name");

serializer.startTag(null, "age");
serializer.text(person.getAge().toString());
serializer.endTag(null, "age");

serializer.endTag(null, "person");
}
serializer.endTag(null, "persons");
serializer.endDocument();
out.flush();
out.close();


16.保存用户偏好设置参数
android:numeric="integer"//只能输入整型
android:onClick="save"//点击事件
save对应activity里的save方法
public void save(String name, Integer age) {
SharedPreferences preferences = context.getSharedPreferences("itcast", Context.MODE_PRIVATE);
Editor editor = preferences.edit();
editor.putString("name", name);
editor.putInt("age", age);
editor.commit();
}
/**
* 获取各项配置参数
* @return
*/
public Map<String, String> getPreferences(){
Map<String, String> params = new HashMap<String, String>();
SharedPreferences preferences = context.getSharedPreferences("itcast", Context.MODE_PRIVATE);
params.put("name", preferences.getString("name", ""));
params.put("age", String.valueOf(preferences.getInt("age", 0)));
return params;
}