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链接数据库

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var MongoClient = require('mongodb').MongoClient,
	assert = require('assert');	// 断言

var url = 'mongodb://localhost:27017/myproject'
MongoClient.connect(url,function(err,db)){
	assert.equal(null,err);	// 如果err == null 继续执行
	console.log('Connected correctly to server');

	db.close();
}

插入文档

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var insertDocument = function(db,callback) {
	var collection = db.collection('document');
	collection.insert([{a:1},{a:2},{a:3}],function(err,result){
		assert.equal(err, null);
    	assert.equal(3, result.result.n);
   		assert.equal(3, result.ops.length);
    	console.log("Inserted 3 documents into the document collection");
    	callback(result);
	});
}

可以在连接时增加

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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    db.close();
  });
});

修改文档

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var updateDocument = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Update document where a is 2, set b equal to 1
  collection.update({ a : 2 }
    , { $set: { b : 1 } }, function(err, result) {
    assert.equal(err, null);
    assert.equal(1, result.result.n);
    console.log("Updated the document with the field a equal to 2");
    callback(result);
  });  
}

也可以在连接时回调

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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      db.close();
    });
  });
});

删除

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var removeDocument = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Insert some documents
  collection.remove({ a : 3 }, function(err, result) {
    assert.equal(err, null);
    assert.equal(1, result.result.n);
    console.log("Removed the document with the field a equal to 3");
    callback(result);
  });    
}
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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');
// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      removeDocument(db, function() {
        db.close();
      });
    });
  });
});

查询

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var findDocuments = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Find some documents
  collection.find({}).toArray(function(err, docs) {
    assert.equal(err, null);
    assert.equal(2, docs.length);
    console.log("Found the following records");
    console.dir(docs)
    callback(docs);
  });      
}
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var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      removeDocument(db, function() {
        findDocuments(db, function() {
          db.close();
        });
      });
    });
  });
});

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Android代码

  1. 获取手机分辨率
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DisplayMetrics dm = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(dm);
int width = dm.widthPixels;
int height = dm.heightPixels;
  1. dp转px
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public static int dip2px(Context context,float dpValue) {
	final float scale = context.getResources().getDisplayMetrics().density;
	return (dpValue *scale + 0.5f);
}
  1. px转dp
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public static int px2dip(Context context,float pxValue) {
	final float scale = context.getResources().getDisplayMetrics().density;
    return (int) (pxValue / scale + 0.5f) - 15;
}
  1. 不需要Context得到density的方法
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Resources.getSystem().getDisplatMetrics().density;

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EventBus是一个非常流行的开源库，用于Android事件发布/订阅，通过解耦发布者和订阅者简化Android事件传递。事件传递可以用于Android四大组件也可以作用于异步线程和主线程的通讯。
相比Handler、BroadCastReceiver、Interface回调，EventBus的优点代码更简洁，使用简单将事件发布和订阅充分解耦。

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再好的应用，也需要有人去发现他，我只是有那么一些途径，让我更快的找到它们而已。有网页，有微博，也有微信公众号，希望我的这些推荐可以让你更好的发现那些优秀、精美的应用。

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  1. 将Android手机的调试模式打开
  2. 按住选择Mac的option键，选择Apple图标选项的系统信息
  3. 找到USB，查看手机的厂商ID，比如我的MX Pro是0x2a45
  4. 在终端中输入并执行echo 0x2a45 >> ~/.android/adb_usb.ini
  5. 重启ADB服务（adb restart或者重启Eclipse、AndroidStudio）