在send方法中,应该将"sms"+receiver改为"sms:"+receiver,以正确设置短信的接收者。正确的代码应该是:
public void send(View view) {
Intent intent = new Intent();
intent.setAction(intent.ACTION_SENDTO);
intent.addCategory("android.intent.category.DEFAULT");
String receiver,message;
receiver=et_receiver.getText().toString();
message=et_content.getText().toString();
intent.setData(Uri.parse("sms:"+receiver));
intent.putExtra("sms_body",message);
startActivity(intent);
}