angular.module('MyModule', [], function($httpProvider) {
	// Use x-www-form-urlencoded Content-Type
	$httpProvider.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded;charset=utf-8';
	/**
	 * The workhorse; converts an object to x-www-form-urlencoded serialization.
	 * @param {Object} obj
	 * @return {String}
	 */
	var param = function(obj) {
		var query = '',
			name, value, fullSubName, subName, subValue, innerObj, i;
		for(name in obj) {
			value = obj[name];
			if(value instanceof Array) {
				for(i = 0; i < value.length; ++i) {
					subValue = value[i];
					fullSubName = name + '[' + i + ']';
					innerObj = {};
					innerObj[fullSubName] = subValue;
					query += param(innerObj) + '&';
				}
			} else if(value instanceof Object) {
				for(subName in value) {
					subValue = value[subName];
					fullSubName = name + '[' + subName + ']';
					innerObj = {};
					innerObj[fullSubName] = subValue;
					query += param(innerObj) + '&';
				}
			} else if(value !== undefined && value !== null)
				query += encodeURIComponent(name) + '=' + encodeURIComponent(value) + '&';
		}
		return query.length ? query.substr(0, query.length - 1) : query;
	};
	// Override $http service's default transformRequest
	$httpProvider.defaults.transformRequest = [function(data) {
		return angular.isObject(data) && String(data) !== '[object File]' ? param(data) : data;
	}];
});
var app = angular.module('wscat', ['MyModule']);
app.controller('loginCtrl', function($scope, $http) {
	$scope.name = 'wscat';
	$scope.submit = function() {
		$http.post('http://localhost/CI/myCi/index.php/login_api/login', {
			params: {
				username: $scope.username,
				password: $scope.password
			}
		}).success(function(data) {
		})
	}
})

public
 function login() {
 	$this -> load -> model('login_model');
 $data = array(
 'user_name' => $this->input->post('params')['username'],
 'password' => md5($this->input->post('params')['password'])
 );
 //or
 var_dump($_POST['params']);
 }

$http({
	method: 'post',
	url: 'http://localhost:8081/search',
	data: {
		"page": page,
		"pageNum": pageNum
	},
	headers: { //1.设置类型
		'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8'
	},
	transformRequest: function(obj) { //2.处理传递参数的格式
		var str = [];
		for(var p in obj) {
			str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]))
		}
		return str.join('&')
	}
}).then(function(data) {
}, function(err) {
});