How to use QOpenGLWidget to draw a triangle correctly?

[MartinChan 0]

Update 2018.01.18:
I solve the question and u can go to here to see the source code.

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Origin Post:
I am trying to write a simple program——to use QOpenGLWidget to draw a colorful triangle but I still can't see the right result. My program zip was here and I put the core codes below ,could anyone tell me what's wrong with my code...? Thx anyway.

glwidget.h:

#ifndef GLWIDGET_H
#define GLWIDGET_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLShaderProgram>
#include <QOpenGLContext>
#include <QOpenGLBuffer>

class GLWidget : public QOpenGLWidget , protected QOpenGLFunctions
{
public:
    GLWidget();
    ~GLWidget();

private:
    void paintGL() Q_DECL_OVERRIDE;
    void initializeGL() Q_DECL_OVERRIDE;
    void resizeGL(int w, int h) Q_DECL_OVERRIDE;

    uchar *fragmentShader;
    uchar *vertexShader;

    QOpenGLShaderProgram *mShaderProgram;
    QOpenGLBuffer vbo;

    GLint a_colorPos;
    GLint a_positionPos;
    GLint u_mvpMatrixPos;

public:

};

#endif // GLWIDGET_H

glwidget.cpp:

#include "glwidget.h"

GLWidget::GLWidget()
{
    mShaderProgram = Q_NULLPTR;
}

GLWidget::~GLWidget()
{

}

void GLWidget::paintGL()
{
    glViewport(0,0,this->width(),this->height());
    glClear(GL_COLOR_BUFFER_BIT);

    mShaderProgram->bind();

    QMatrix4x4 matrix;
    matrix.ortho(-10.0f,10.0f,-10.0f,10.0f,-100.0f,100.0f);
    matrix.translate(0,0,-2);
    mShaderProgram->setUniformValue(u_mvpMatrixPos, matrix);

    glDrawArrays(GL_TRIANGLES,0,3);

//    glDisableVertexAttribArray(a_colorPos);
//    glDisableVertexAttribArray(a_positionPos);

    mShaderProgram->release();
}

void GLWidget::initializeGL()
{
static const char shader1[] =
            "uniform highp mat4 u_mvpMatrix;        \n"
            "attribute highp vec4 a_position;       \n"
            "attribute lowp vec4 a_color;           \n"
            "varying lowp vec4 v_color;             \n"
            "void main()                            \n"
            "{                                      \n"
            "   v_color = a_color;                     \n"
            "   gl_Position = u_mvpMatrix * a_position;\n"
            "}                                      \n";
static const char shader2[] =
            "varying lowp vec4 v_color;             \n"
            "void main()                            \n"
            "{                                      \n"
            "   gl_FragColor = v_color;                \n"
            "}                                      \n";

    initializeOpenGLFunctions();

    if ( !mShaderProgram )
    {
        mShaderProgram = new QOpenGLShaderProgram(this);
        mShaderProgram->addShaderFromSourceCode(QOpenGLShader::Vertex,shader1);
        mShaderProgram->addShaderFromSourceCode(QOpenGLShader::Fragment,shader2);
        mShaderProgram->link();
        a_positionPos  = mShaderProgram->attributeLocation("a_positionPos");
        a_colorPos     = mShaderProgram->attributeLocation("a_color");
        u_mvpMatrixPos = mShaderProgram->uniformLocation("u_mvpMatrix");

        vbo.create();
        vbo.bind();

        GLfloat vVertices[] = {
            0.0f, 0.5f, 0.0f,
           -0.5f,-0.5f, 0.0f,
            0.5f,-0.5f, 0.0f
        } ;
        GLfloat vColors[]   = {
            1.0f, 0.0f, 0.0f,
            0.0f, 1.0f, 0.0f,
            0.0f, 0.0f, 1.0f
        };

        vbo.allocate(vVertices,18*sizeof(GLfloat));
        mShaderProgram->setAttributeBuffer(a_positionPos,GL_FLOAT,0,3,0);
        glEnableVertexAttribArray(a_positionPos);

        vbo.write(9*sizeof(GLfloat),vColors,9*sizeof(GLfloat));
        mShaderProgram->setAttributeBuffer(a_colorPos,GL_FLOAT,9*sizeof(GLfloat),3,0);
        glEnableVertexAttribArray(a_colorPos);

//        glVertexAttribPointer(a_positionPos,3,GL_FLOAT,GL_FALSE,0,vVertices);
//        glVertexAttribPointer(a_colorPos   ,3,GL_FLOAT,GL_FALSE,0,vColors  );
    }

    glClearColor(0.0,0.0,0.0,1.0);

}

void GLWidget::resizeGL(int w, int h)
{

}