base64传后台中文乱码

jQuery.base64= ( function( $) {

    var _PADCHAR = "=",

        _ALPHA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",

        _VERSION = "1.1";//Mr. Ruan fix to 1.1 to support asian char(utf8)

    function _getbyte64( s, i) {

        // This is oddly fast, except on Chrome/V8.

// Minimal or no improvement in performance by using a

// object with properties mapping chars to value (eg. 'A': 0)

        var idx = _ALPHA.indexOf( s.charAt( i) );

        if ( idx === -1 ) {

            throw "Cannot decode base64";

        }

        return idx;

    }

    function _decode_chars(y, x){

        while(y.length> 0){

            var ch = y[0];

            if(ch < 0x80) {

                y.shift();

                x.push(String.fromCharCode(ch));

            }else if((ch & 0x80) == 0xc0){

                if(y.length< 2) break;

                ch = y.shift();

                var ch1 = y.shift();

                x.push(String.fromCharCode( ((ch & 0x1f) << 6) + (ch1 & 0x3f)));

            }else{

                if(y.length< 3) break;

                ch = y.shift();

                var ch1 = y.shift();

                var ch2 = y.shift();

                x.push(String.fromCharCode(((ch & 0x0f) << 12) + ((ch1 & 0x3f) << 6) + (ch2 & 0x3f)));

            }

}

}

    function _decode( s) {

        var pads = 0,

            i,

            b10,

            imax = s.length,

            x = [],

            y = [];

        s= String( s);

        if ( imax === 0 ) {

            return s;

        }

        if ( imax % 4 !== 0 ) {

            throw "Cannot decode base64";

        }

        if ( s.charAt( imax - 1 ) === _PADCHAR ) {

            pads = 1;

            if ( s.charAt( imax - 2 ) === _PADCHAR ) {

                pads = 2;

            }

            // either way, we want to ignore this last block

            imax -= 4;

        }

        for ( i = 0; i < imax; i += 4 ) {

            var ch1 = _getbyte64( s, i );

            var ch2 = _getbyte64( s, i + 1);

            var ch3 = _getbyte64( s, i + 2);

            var ch4 = _getbyte64( s, i + 3);

            b10 = ( _getbyte64( s, i ) << 18 ) | ( _getbyte64( s, i + 1 ) << 12 ) | ( _getbyte64( s, i + 2 ) << 6 ) | _getbyte64( s, i + 3 );

            y.push(b10 >> 16);

            y.push((b10 >> 8) & 0xff);

            y.push(b10 & 0xff);

            _decode_chars(y, x);

        }

        switch ( pads ) {

            case 1:

                b10 = ( _getbyte64( s, i ) << 18 ) | ( _getbyte64( s, i + 1 ) << 12 ) | ( _getbyte64( s, i + 2 ) << 6 );

                y.push(b10 >> 16);

                y.push((b10 >> 8) & 0xff);

break;

            case 2:

                b10 = ( _getbyte64( s, i ) << 18) | ( _getbyte64( s, i + 1 ) << 12 );

                y.push(b10 >> 16);

break;

        }

        _decode_chars(y, x);

        if(y.length> 0) throw "Cannot decode base64";

        return x.join( "" );

    }

    function _get_chars(ch, y){

        if(ch< 0x80) y.push(ch);

        else if(ch< 0x800){

            y.push(0xc0 + ((ch>> 6) & 0x1f));

            y.push(0x80 + (ch& 0x3f));

        }else{

            y.push(0xe0 + ((ch>> 12) & 0xf));

            y.push(0x80 + ((ch>> 6) & 0x3f));

            y.push(0x80 + (ch& 0x3f));

        }

}

    function _encode( s) {

        if ( arguments.length!== 1 ) {

            throw "SyntaxError: exactly one argument required";

        }

        s= String( s);

        if ( s.length=== 0 ) {

            return s;

        }

        //s = _encode_utf8(s);

        var i,

            b10,

            y = [],

            x = [],

            len = s.length;

        i = 0;

        while(i < len){

            _get_chars(s.charCodeAt(i), y);

            while(y.length>= 3){

                var ch1 = y.shift();

                var ch2 = y.shift();

                var ch3 = y.shift();

                b10 = ( ch1 << 16 ) | ( ch2 << 8 ) | ch3;

                x.push( _ALPHA.charAt( b10 >> 18 ) );

                x.push( _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) );

                x.push( _ALPHA.charAt( ( b10 >> 6 ) & 0x3f ) );

                x.push( _ALPHA.charAt( b10 & 0x3f ) );

            }

            i++;

        }

        switch ( y.length) {

            case 1:

                var ch = y.shift();

                b10 = ch << 16;

                x.push( _ALPHA.charAt( b10 >> 18 ) + _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) + _PADCHAR + _PADCHAR );

break;

            case 2:

                var ch1 = y.shift();

                var ch2 = y.shift();

                b10 = ( ch1 << 16 ) | ( ch2 << 8 );

                x.push( _ALPHA.charAt( b10 >> 18 ) + _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) + _ALPHA.charAt( ( b10 >> 6 ) & 0x3f ) + _PADCHAR );

break;

        }

        return x.join( "" );

    }

    return {

        decode: _decode,

        encode: _encode,

        VERSION: _VERSION

    };

}( jQuery) );

前端调用测试

var name=$.base64.encode("测试"),

BASE64Decoder decoder=new BASE64Decoder();

byte[] bytes = Base64.decodeBase64(name);

String ss=new String(bytes);