核心代码
public class MyDatabaseHelper extends SQLiteOpenHelper{
public static final String CREATE_BOOK = "create table Book("
+"id integer primary key autoincrement,"
+"author text," +
"price real," +
"pages integer," +
"name text)";
public static final String CREARE_CATEGORY = "create table Category("
+"id integer primary key autoincrement," +
"category_name text," +
"category_code integer)";
private Context mContext;
public MyDatabaseHelper(Context context,String name,CursorFactory factory,int version){
super(context,name,factory,version);
mContext = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(CREATE_BOOK);
db.execSQL(CREARE_CATEGORY);
Toast.makeText(mContext, "create succeeded", Toast.LENGTH_SHORT).show();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("drop table if exists Book");
db.execSQL("drop table if exists Category");
onCreate(db);
}
}<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dp" >
<LinearLayout
android:id="@+id/left_layout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left"
android:background="@drawable/left" >
<TextView
android:id="@+id/left_msg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:textColor="#fff" />
</LinearLayout>
<LinearLayout
android:id="@+id/right_layout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:background="@drawable/right" >
<TextView
android:id="@+id/right_msg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp" />
</LinearLayout>
</LinearLayout> MainActivity
public class MainActivity extends Activity {
private ListView msgListView;
private EditText inputText;
private Button send;
private MsgAdapter adapter;
private List<Msg>msgList=new ArrayList<Msg>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
initMsgs();
adapter=new MsgAdapter(MainActivity.this,R.layout.msg_item,msgList);
inputText=(EditText) findViewById(R.id.input_text);
send=(Button) findViewById(R.id.send);
msgListView=(ListView) findViewById(R.id.msg_list_view);
msgListView.setAdapter(adapter);
send.setOnClickListener(new OnClickListener(){
public void onClick(View v){
String content=inputText.getText().toString();
if(!"".equals(content)){
Msg msg=new Msg(content,Msg.TYPE_SEND);
msgList.add(msg);
adapter.notifyDataSetChanged();
msgListView.setSelection(msgList.size());
inputText.setText("");
}
}
});
}
private void initMsgs(){
Msg msg1=new Msg("Hello guy.",Msg.TYPE_RECEIVED);
msgList.add(msg1);
Msg msg2=new Msg("Hello.Who is that?",Msg.TYPE_SEND);
msgList.add(msg2);
Msg msg3=new Msg("This is Tom.Nice talking to you.",Msg.TYPE_RECEIVED);
msgList.add(msg3);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
} public class Msg {
public static final int TYPE_RECEIVED = 0;
public static final int TYPE_SEND = 1;
private String content;
private int type;
public Msg(String content, int type) {
this.content = content;
this.type = type;
}
public String getContent() {
return content;
}
public int getType() {
return type;
}
} MsgAdapter.java
public class MsgAdapter extends ArrayAdapter<Msg>{
private int resourceId;
public MsgAdapter(Context context,int textViewResourceId,List<Msg>objects){
super(context,textViewResourceId,objects);
resourceId=textViewResourceId;
}
public View getView(int position,View convertView,ViewGroup parent){
Msg msg=getItem(position);
View view;
ViewHolder viewHolder;
if(convertView==null){
view=LayoutInflater.from(getContext()).inflate(resourceId, null);
viewHolder=new ViewHolder();
viewHolder.leftLayout=(LinearLayout)view.findViewById(R.id.left_layout);
viewHolder.rightLayout=(LinearLayout)view.findViewById(R.id.right_layout);
viewHolder.leftMsg=(TextView)view.findViewById(R.id.left_msg);
viewHolder.rightMsg=(TextView)view.findViewById(R.id.right_msg);
view.setTag(viewHolder);
}else{
view=convertView;
viewHolder=(ViewHolder)view.getTag();
}
if(msg.getType()==Msg.TYPE_RECEIVED){
viewHolder.leftLayout.setVisibility(View.VISIBLE);
viewHolder.rightLayout.setVisibility(View.GONE);
viewHolder.leftMsg.setText(msg.getContent());
}else if(msg.getType()==Msg.TYPE_SEND){
viewHolder.rightLayout.setVisibility(View.VISIBLE);
viewHolder.leftLayout.setVisibility(View.GONE);
viewHolder.rightMsg.setText(msg.getContent());
}
return view;
}
class ViewHolder{
LinearLayout leftLayout;
LinearLayout rightLayout;
TextView leftMsg;
TextView rightMsg;
}
}