http断点续传简单实现（java)

/* }%B^Vl%ZZ  
**SiteFileFetch.java z}vgp\cuT  
*/ *_puW x  
package NetFox; &}P{w  
import java.io.*; D=U"L-rRs  
import java.net.*; t0*JinKI  
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public class SiteFileFetch extends Thread { }| BnG"8  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Nj Ng=q  
long[] nStartPos; //开始位置 5Uc!;Gd?b  
long[] nEndPos; //结束位置 ad).X:Qs  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 >qjQ;z[  
long nFileLength; //文件长度 ULq#2l  
boolean bFirst = true; //是否第一次取文件 d>z?JDt  
boolean bStop = false; //停止标志 =6Dz<Lq  
File tmpFile; //文件下载的临时信息 Z[G
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DataOutputStream output; //输出到文件的输出流 E"D+CD0  
Sq,ZzMw  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） s7?Q[vN  
public SiteFileFetch(SiteInfoBean bean) throws IOException F2yc&mXyk  
{ |kL^k{=zV  
siteInfoBean = bean; sGjYL>*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +@wa?"  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); H@$\SUc{  
if(tmpFile.exists ()) a)'^'jm)4  
{ v%|^\A"V  
bFirst = false; Z}(,OZh  
read_nPos(); Z!Njfq5  
} -AUdBG  
else {O-,JCq/  
{ aZGX`;3  
nStartPos = new long[bean.getNSplitter()]; w,(e,8#:  
nEndPos = new long[bean.getNSplitter()]; )K2,h5zU  
} F0O"rN{  
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} 6$TE-l  
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public void run() nmlQ-V-  
{ : [o0Va2 d  
//获得文件长度 k23*F0Dv  
//分割文件 Vk/CV2  
//实例FileSplitterFetch mAkR<\?iTF  
//启动FileSplitterFetch线程 *Z*4L|zT  
//等待子线程返回 d5gYJ/Qv  
try{ ,&S:(b[D  
if(bFirst) &D,gKT~  
{ (,~gY=E+  
nFileLength = getFileSize(); LFHV~>d  
if(nFileLength == -1) ek~bXy{O`  
{ XJl2_
#  
System.err.println("File Length is not known!"); *rPUVhD_  
} 5a1)`2V2M  
else if(nFileLength == -2) iGmBG1a\  
{ >'3J. FY  
System.err.println("File is not access!"); :*V1jp+  
} ^;0.P)yGA  
else 3dG[dYj  
{ ^a~^$PUqI  
for(int i=0;i<nStartPos.length;i++) ~W'>L++  
{ wehZ7eqm  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); "Gx(-NH+  
} f5jxF"oGNo  
for(int i=0;i<nEndPos.length-1;i++) Q70LQCms  
{ %\8E{M:  
nEndPos = nStartPos[i+1]; x{IxS?.j+  
} Z)cGe1?q  
nEndPos[nEndPos.length-1] = nFileLength; gR)T(%W  
} YNCQPN\v`1  
} O-r,&W  
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//启动子线程 <$)F_R~T3  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; w8M,35b  
for(int i=0;i<nStartPos.length;i++) .Ua|KKK C  
{ xh[De}@  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 5 3=zH
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), b]s.h8+v;  
nStartPos,nEndPos,i); 4:Adn?"  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `!<RP'  
fileSplitterFetch.start(); %dMq'j  
} 0q`n]NM  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .du FMJl  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 5}FPqyK"  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", /7Z;/|oU  
nEndPos = " + nFileLength); J8[N!qDCj  
// fileSplitterFetch[nPos.length-1].start(); )0Av:
eF-+  
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a>jiq8d]4  
//等待子线程结束 Y#Pl)sRr  
//int count = 0; ndEW$?W,  
//是否结束while循环 1PLxc)LsG  
boolean breakWhile = false; Z'EXq.hk  
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while(!bStop)  S^;D\6(r  
{ A;E7~qOG  
write_nPos(); Qzbelt@Wx  
Utility.sleep(500); !"{+|heU9p  
breakWhile = true; p3Uus''V4  
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)*_4=-8H  
for(int i=0;i<nStartPos.length;i++) CCp&P5[67  
{ I9GRSm;0<  
if(!fileSplitterFetch.bDownOver) JR='c)6:  
{ yM(zc/?  
breakWhile = false; >,22@4  
break; <t[WHDO`  
} S'"(zc3=  
} __jFSa`at  
if(breakWhile) ~Y^ UP  
break; l!z0lh-J  
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//count++; o)<c1\q  
//if(count>4) _+z5~6>  
// siteStop(); =bm<>h7.)  
} z>HeM Mei  
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System.err.println("文件下载结束！"); %j9'HtjEa  
} <a_Q1 l  
catch(Exception e){e.printStackTrace ();} Bd8,~8  
} oW]~\vp^0  
^3*k6h[(  
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//获得文件长度 :

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public long getFileSize() >% a^;gk(  
{ Wx&gI4~  
int nFileLength = -1; L$*sv.  
try{ S0+nQM%  
URL url = new URL(siteInfoBean.getSSiteURL()); $
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); }$-;P=k  
httpConnection.setRequestProperty("User-Agent","NetFox"); T@c{5a  
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int responseCode=httpConnection.getResponseCode(); iYE:o{  
if(responseCode>=400) Aa^%_5  
{ i^LLKx7M&  
processErrorCode(responseCode); kI5`[\  
return -2; //-2 represent access is error Y{~[N yE  
} 78't"2>  
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String sHeader; a!ao{8#  
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for(int i=1;;i++)
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{ >q{E9.~b  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ~4YU  
//Utility.log(in.readLine());  f,utA3[  
sHeader=httpConnection.getHeaderFieldKey(i); vMOI&_[\z  
if(sHeader!=null)  3LKL,z  
{ e)I-|Q4^%  
if(sHeader.equals("Content-Length")) $J8?!Xg  
{ fz H$`X'M  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); S+LE ASOr  
break; 1^<R2x  
} We]mm3M3  
} ]+RBykr  
else .32]$v
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break; Nrp0z:  
} RLkP)+t  
} +m Plid\  
catch(IOException e){e.printStackTrace ();} md8r"  
catch(Exception e){e.printStackTrace ();} v`i9LD0(  
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Utility.log(nFileLength); 5(F @KeH>  
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return nFileLength; X.)caF^j  
} fh rS7f'Zd  
|q&&"SpA  
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//保存下载信息（文件指针位置） y8/ 7@qw  
private void write_nPos() !F3Y7R  
{ i@7b  
try{ ,1-n=eTQ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); EC*rd  
output.writeInt(nStartPos.length); r=8(n<;Co  
for(int i=0;i<nStartPos.length;i++) V[&4Km9C  
{ t#pF.!9=  
// output.writeLong(nPos); D@:w/W  
output.writeLong(fileSplitterFetch.nStartPos); +k=BD s  
output.writeLong(fileSplitterFetch.nEndPos); t;ZA}>/  
} aYIAy]*1e  
output.close(); SM3Q29XIw  
} {<f_,Nlc  
catch(IOException e){e.printStackTrace ();} S%ULGX:@ga  
catch(Exception e){e.printStackTrace ();} ESdjDg$[u  
} .GG6wL<$?  
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//读取保存的下载信息（文件指针位置） g8<Ja
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private void read_nPos() .QRa{l_)  
{ 7s#,.(s  
try{ {%Mt-Gm'd  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); d51.Tbt#%7  
int nCount = input.readInt(); 6$#p}nE  
nStartPos = new long[nCount]; <3aiS?i.h  
nEndPos = new long[nCount]; f=0U&~  
for(int i=0;i<nStartPos.length;i++) wvH=4TT=w"  
{ nt$VH  
nStartPos = input.readLong(); m0I/X$-Cl5  
nEndPos = input.readLong(); O>
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} y#%*aV}|B  
input.close(); [T8BQn!  
} 2)O-EAn  
catch(IOException e){e.printStackTrace ();} JO*}\
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catch(Exception e){e.printStackTrace ();} n)]]g3y2  
} KMFvi_8  
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private void processErrorCode(int nErrorCode) EJF*_<f9O  
{ MfzSoxCb  
System.err.println("Error Code : " + nErrorCode); 6y;R1z b  
} t[L0kF9en  
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//停止文件下载 %`rZ]^H  
public void siteStop() lFHj]%Y  
{ AF-4b*oB  
bStop = true; {<\[gm\X
 
for(int i=0;i<nStartPos.length;i++) D]NfA2B7  
fileSplitterFetch.splitterStop(); Ns^[Hb[b'  
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} zR)9]p
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} ^zdZ"\x  
//负责部分文件的抓取 xj/Iq<'R*O  
**FileSplitterFetch.java lO?dI=}]  
*/ tvh)N{j  
package NetFox; gEFs4; CN  
+mc0:e{WF  
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import java.io.*; 5u(B]_r.  
import java.net.*; (<|NerwD  
C_c*21X  
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public class FileSplitterFetch extends Thread { N~<H`  
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String sURL; //File URL $j ZU(<4,  
long nStartPos; //File Snippet Start Position y81B3`@  
long nEndPos; //File Snippet End Position
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int nThreadID; //Thread's ID F\
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boolean bDownOver = false; //Downing is over Re`'dde=  
boolean bStop = false; //Stop identical l]pHj4`uv  
FileAccessI fileAccessI = null; //File Access interface a@>P?N~LA9  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Fo$kD(  
{ }ioHSkCD  
this.sURL = sURL; 7hg)R @OC  
this.nStartPos = nStart; ]!v:xjzT  
this.nEndPos = nEnd;  4[\[Ho  
nThreadID = id; jJ(()EJ  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 m[k@\xS4e  
} =wd=TX/  
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public void run() Wmm'j&hI  
{ w=ZSyT-i  
while(nStartPos < nEndPos && !bStop) Q db~I#}m'  
{ G
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try{ 7RH1,k  
URL url = new URL(sURL); SHc<`M'+  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); DU@ZLk3  
httpConnection.setRequestProperty("User-Agent","NetFox"); %Ls5:Z=  
String sProperty = "bytes="+nStartPos+"-"; L?WF[nFR  
httpConnection.setRequestProperty("RANGE",sProperty); G;^},%<  
Utility.log(sProperty); XOk0_[
 
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InputStream input = httpConnection.getInputStream(); >?pWbL  
//logResponseHead(httpConnection); BqF%2{  
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byte[] b = new byte[1024]; ]Wn^m+  
int nRead; =th(Hdk17  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) k7R8Q~4  
{ N-lo[bDJh  
nStartPos += fileAccessI.write(b,0,nRead); dKKh^D`~  
//if(nThreadID == 1) Z9TUaMhF  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Y?1 3_~ K  
} o$S/EZ  
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Utility.log("Thread " + nThreadID + " is over!"); +{qX,  
bDownOver = true; Q9Y$x{R&  
//nPos = fileAccessI.write (b,0,nRead); 7K*\F}2)q  
} , Ww\C  
catch(Exception e){e.printStackTrace ();} N2 vA/  
} FEdWe\E  
} m!Iax]D{  
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//打印回应的头信息 ~^6[SbVb  
public void logResponseHead(HttpURLConnection con) }qqE2;{ND  
{ Awip qDAu  
for(int i=1;;i++) o@p(8=x  
{ PYOU=R%o`8  
String header=con.getHeaderFieldKey(i); zK*zT$<l  
if(header!=null) `|t X[':  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); a!_vd B  
Utility.log(header+" : "+con.getHeaderField(header)); b1("(,r/`  
else <c,/+ lQ^  
break; .e^AS~4pl  
} (%i)A$i6a  
} c h_1-  
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public void splitterStop() stb)Tl^  
{ Ql%0%naq1  
bStop = true; h{$mL#J  
} Vy+%sG q"  
4 ^=qc99  
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} [(hB%x_"  
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/* Sxj _gn   
**FileAccess.java #[4MwM3  
*//文件访问(定位，写) YTQom!O  
package NetFox; 17itC9U  
import java.io.*; wFgL\[$^|  
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public class FileAccessI implements Serializable{ :X?bWxOJ  
s+=JT+g  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 P,(Tu.EPk  
RandomAccessFile oSavedFile; l$i^e|*  
long nPos; w6^X*tE  
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7 Q`'1oE?  
public FileAccessI() throws IOException $IuN(#  
{ EB/.M+~a  
this("",0); !uC`7a  
} }G:5P3f  
+cDz`)N,,  
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public FileAccessI(String sName,long nPos) throws IOException R)%1GG4  
{ yf2I%\p}  
oSavedFile = new RandomAccessFile(sName,"rw"); 5i 6*$#OM_  
this.nPos = nPos; K*ZH<@o4  
oSavedFile.seek(nPos); +npcU:(Kg  
} _li\b-  
%(EUZu2  
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public synchronized int write(byte[] b,int nStart,int nLen) S
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{ 4. &t  
int n = -1; Y|s?9'z  
try{ cY}Nr#%s@U  
oSavedFile.write(b,nStart,nLen); q ;@
:,^  
n = nLen; Oy @vh>RY  
} =<_ei|ME  
catch(IOException e) ~7N>tjB  
{ Ik92='Z  
e.printStackTrace (); dIOj]5H3F  
} *ybwlLg  
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return n; q=o"] 6  
} Qx_K)  
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} "S">#.L  
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/* q{rc[ s?  
**SiteInfoBean.java $] js0)>  
*/ \X'{ ee  
package NetFox; a"!D@a  
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public class SiteInfoBean { .kBZ(`K  
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private String sSiteURL; //Site's URL lS`hJ:  
private String sFilePath; //Saved File's Path :QSCky*i  
private String sFileName; //Saved File's Name \XG18V&  
private int nSplitter; //Count of Splited Downloading File -&#H@Gyw  
s}~'o!}W  
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public SiteInfoBean() ++s=$D  
{//nSplitter的缺省值为5 zH0{S.3k  
//default value of nSplitter is 5 lC/4CPKtV  
this("","","",5); :Kc}R)6  
} q><E?  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) n3-2;xuNKE  
{ zuWfR&U|W  
sSiteURL= sURL; D@Zb|EI%<  
sFilePath = sPath;
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sFileName = sName; }y-b<J?H  
this.nSplitter = nSpiltter; KUC(n!  
-L9I;]:KY  
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} oSb,)k@  
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public String getSSiteURL() DqLZc01>  
{ :v_H;UU  
return sSiteURL; [l+1zt0w0  
} sK#)wjj\^  
9d7$Fz#  
py,B6UB5  
public void setSSiteURL(String value) c3\z  
{ |eEcEu?/b  
sSiteURL = value; d83K;Ryd  
} RV
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public String getSFilePath() XO)|l8t#$=  
{ T)IH4UO  
return sFilePath; bK)gB!  
} +4kBd<0Y  
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public void setSFilePath(String value) *siN#
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{ }gE?ms4$  
sFilePath = value; Ok-*xd  
} Az_s"}G  
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public String getSFileName() {DPobyvwFk  
{ R@=Bk(h  
return sFileName; ^cYm.EHI  
} ~E2xIhV  
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public void setSFileName(String value) v3(W4G`  
{ bg\~"  
sFileName = value; Kt,ENbF  
} e]\{ Ia  
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public int getNSplitter() `>@n6>f  
{ kan?2x  
return nSplitter; ^-3R+U- S  
} 90%alG1>y  
)v!>U<eprD  
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public void setNSplitter(int nCount) 'F'v/G~
F  
{ ';buS -|6  
nSplitter = nCount; s=lkK/ [  
} $]/a/!d  
} Z3K~C_0Cnu  
lFT_J?G$'  
'1{#I/P;  
/* dP(*IOO.  
**Utility.java K!q:A+]  
*/ hJ0)"OA5  
package NetFox; 4Fr0/="H  
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$7{V+>  
public class Utility { {1^9*  
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p]*BeiT#n%  
public Utility() <~BheGmmy  
{ {`0GAW)q  
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/? n 9c;w  
} @0`Q  
lZTD>$  
//线程睡眠 wL]7d3t  
public static void sleep(int nSecond) * %p6+D-C  
{ CVsc#=w0  
try{ @P:  
Thread.sleep(nSecond); W{\){fr6O  
} g)+45w*+5  
catch(Exception e) Xp]tL3-p  
{ *N"bn'>3  
e.printStackTrace (); 3IqYpK(s  
} n237%LH[  
} CErkmod{}e  
f!}c0nb  
//日志 :%Dw3IrOM  
public static void log(String sMsg) h(hb?f@1:  
{ ]9?_m@Ihx  
System.err.println(sMsg); ^
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} :('7ly!h  
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s}Q%]W  
public static void log(int sMsg) dKcHj<'E/  
{ p1 tfN$-  
System.err.println(sMsg); ^a@Vn\V1  
} X*Mw0;+T  
} v>TI.;{y  
WP1>)  
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/* `, ?T;JRc  
**TestMethod.java !*wK4UcX"  
*/ iG*3S)  
package NetFox; %J\1W"I?  
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public class TestMethod { 6N >ksqo8%  
mqGp]'{  
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public TestMethod() .IYE+XzV  
{ ///xx/weblogic60b2_win.exe S2)rkX
$  
try{ ,,r%Y&:`6  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); yKEE @@}\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); KYY~ YP  
SiteFileFetch fileFetch = new SiteFileFetch(bean); v2 [ l$  
fileFetch.start(); *B(na+  
} ,D-VC{lj  
catch(Exception e){e.printStackTrace ();} UO}Kk*  
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} i*j[j~2>C;  
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W`]
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public static void main(String[] args) !8]W"@qb  
{ DJlY~}v#_  
new TestMethod(); /OaLkENgvf  
} VmrW\rH@  
} 9="i'nYp  
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