[移动开发]Android通过webview实现手写签名并上传服务器

MainActivity 签名页面

package com.sign.webview;

import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.webkit.ValueCallback;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends Activity {

    private WebView _webview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        _webview = findViewById(R.id.webview);
        _webview.getSettings().setJavaScriptEnabled(true);
        _webview.getSettings().setAllowUniversalAccessFromFileURLs(true);
        _webview.setWebViewClient(new WebViewClient());
        _webview.addJavascriptInterface(new Bridge(), "bridge");
        _webview.loadUrl("file:///android_asset/index.html");
        findViewById(R.id.btn_clear).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                _webview.loadUrl("javascript:clear()");
            }
        });
        findViewById(R.id.btn_save).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    System.out.println("============ 开始保存 ============");
                    _webview.evaluateJavascript("save()", new ValueCallback<String>() {
                        @Override
                        public void onReceiveValue(String value) {
                            System.out.println("============ 保存结束 ============" + Bridge.sb);
                            Intent intent = new Intent(MainActivity.this,Main2Activity.class);
                            intent.putExtra("url", String.valueOf(Bridge.sb));
                            startActivity(intent);
                        }
                    });
                }
            }
        });
    }

}

MainActivity 布局文件

<?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">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <Button
            android:id="@+id/btn_clear"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="清空" />

        <Button
            android:id="@+id/btn_save"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="保存" />
    </LinearLayout>

    <WebView
        android:id="@+id/webview"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </WebView>

</LinearLayout>

保存后的字符串拼接转为bitmap图片显示

package com.sign.webview;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Base64;
import android.util.Log;
import android.widget.ImageView;

public class Main2Activity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        ImageView imageView = findViewById(R.id.image);
        String url = getIntent().getStringExtra("url");
        imageView.setImageBitmap(stringtoBitmap(Stringbehind(url,"data:image/png;base64,")));//截取data:image/png;base64
    }
    public static String Stringbehind(String content, String string) {
        //截取之后的字符
        int length = string.length();
        String str = content.substring(content.indexOf(string));
        return str.substring(length);
    }
    public Bitmap stringtoBitmap(String string) {
        //将字符串转换成Bitmap类型
        Bitmap bitmap = null;
        try {
            byte[] bitmapArray;
            bitmapArray = Base64.decode(string, Base64.DEFAULT);
            bitmap = BitmapFactory.decodeByteArray(bitmapArray, 0, bitmapArray.length);
        } catch (Exception e) {
            e.printStackTrace();
            Log.e("xhx", "base64转换图片异常");
        }

        return bitmap;
    }
}

本地所需签名文件请在demo中下载

签名demo链接