refine opencv build

tests/prepare.sh

@@ -85,13 +85,16 @@ if [ ${MODE} = "cpp_infer" ];then
     cd deploy/cpp_infer
     use_opencv=$(func_parser_value "${lines[52]}")
     if [ ${use_opencv} = "True" ]; then
+        if [ -d "opencv-3.4.7/opencv3/" ] && [ $(md5sum opencv-3.4.7.tar.gz | awk -F ' ' '{print $1}') = "faa2b5950f8bee3f03118e600c74746a" ];then
+            echo "################### build opencv skipped ###################"
+        else
             echo "################### build opencv ###################"
-        rm -rf 3.4.7.tar.gz opencv-3.4.7/
-        wget https://github.com/opencv/opencv/archive/3.4.7.tar.gz
-        tar -xf 3.4.7.tar.gz
+            rm -rf opencv-3.4.7.tar.gz opencv-3.4.7/
+            wget https://paddleocr.bj.bcebos.com/dygraph_v2.0/test/opencv-3.4.7.tar.gz
+            tar -xf opencv-3.4.7.tar.gz
 
             cd opencv-3.4.7/
-        install_path=$(pwd)/opencv-3.4.7/opencv3
+            install_path=$(pwd)/opencv3
 
             rm -rf build
             mkdir build
@@ -120,6 +123,7 @@ if [ ${MODE} = "cpp_infer" ];then
             cd ../
             echo "################### build opencv finished ###################"
         fi
+    fi
 
 
     echo "################### build PaddleOCR demo ####################"